Implantable layers for a surgical instrument

ABSTRACT

A staple cartridge is disclosed. The staple cartridge can include a cartridge body, a plurality of staples, and an implantable layer. The implantable layer can include a piece of lyophilized foam and a plurality of fibers at least partially embedded in the piece of lyophilized foam. The implantable layer can further include a plurality of pores defined in piece of lyophilized foam, and a plurality of pockets, wherein a pocket at least partially surrounds a fiber. A method of forming an implantable layer for use with a surgical staple is also disclosed. The method can comprise obtaining a mold comprising a cavity, placing a plurality of fibers in the cavity of the mold, dispensing a solution into the cavity around the fibers, and lyophilizing the solution in the cavity.

BACKGROUND

The present invention relates to surgical instruments and, in variousembodiments, to surgical stapling and cutting instruments and staplecartridges for use therewith.

A stapling instrument can include a pair of cooperating elongate jawmembers, wherein each jaw member can be adapted to be inserted into apatient and positioned relative to tissue that is to be stapled and/orincised. In various embodiments, one of the jaw members can support astaple cartridge with at least two laterally spaced rows of staplescontained therein, and the other jaw member can support an anvil withstaple-forming pockets aligned with the rows of staples in the staplecartridge. Generally, the stapling instrument can further include apusher bar and a knife blade which are slidable relative to the jawmembers to sequentially eject the staples from the staple cartridge viacamming surfaces on the pusher bar and/or camming surfaces on a wedgesled that is pushed by the pusher bar. In at least one embodiment, thecamming surfaces can be configured to activate a plurality of stapledrivers carried by the cartridge and associated with the staples inorder to push the staples against the anvil and form laterally spacedrows of deformed staples in the tissue gripped between the jaw members.In at least one embodiment, the knife blade can trail the cammingsurfaces and cut the tissue along a line between the staple rows.

The foregoing discussion is intended only to illustrate various aspectsof the related art in the field of the invention at the time, and shouldnot be taken as a disavowal of claim scope.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features of the embodiments described herein, together withadvantages thereof, may be understood in accordance with the followingdescription taken in conjunction with the accompanying drawings.

FIG. 1 is a cross-sectional perspective view of a portion of animplantable layer, in accordance with at least one embodiment of thepresent disclosure.

FIG. 2 is a cross-sectional elevation view of a portion of a staplecartridge including an implantable layer and a portion of a stapledepicting the staple in an unfired position and an undeformedconfiguration, in accordance with at least one embodiment of the presentdisclosure.

FIG. 3 is a cross-sectional elevation view of the staple of FIG. 2 in afired position and a deformed configuration, and further depictingtissue along with a portion of the implantable layer of FIG. 2 capturedwithin the staple.

FIG. 4 is a perspective view of an implantable layer with a portion ofthe layer cutaway to reveal pores and tissue ingrowth passages withinthe implantable layer, and further depicting passage-forming punchesextending into the implantable layer, in accordance with at least oneembodiment of the present disclosure.

FIG. 5 is a cross-sectional elevation view of a portion of animplantable layer depicting tissue ingrowth along passages in theimplantable layer, in accordance with at least one embodiment of thepresent disclosure.

FIG. 6 is a perspective view of an implantable layer including a porouslayer and a fibrous layer and with a portion of the fibrous layerremoved to reveal the underlying porous portion, in accordance with atleast one embodiment of the present disclosure.

FIG. 7 is a cross-sectional elevation view of a portion of theimplantable layer of FIG. 6.

FIG. 8 is a cross-sectional perspective view of the implantable layer ofFIG. 6 depicting the implantable layer and tissue captured within afired and deformed staple.

FIG. 9 is a perspective view of an implantable layer, in accordance withat least one embodiment of the present disclosure.

FIG. 10 is a perspective view of a fibrous mesh pocket, in accordancewith at least one embodiment of the present disclosure.

FIG. 11 is a perspective view of a portion of an implantable layer, inaccordance with at least one embodiment of the present disclosure.

FIG. 12 is a cross-sectional elevation view of a portion of a staplecartridge including an implantable layer and a staple depicting thestaple in an unfired position and an undeformed configuration, inaccordance with at least one embodiment of the present disclosure.

FIG. 13 is a cross-sectional elevation view of the staple of FIG. 12 ina fired position and a deformed configuration, and further depictingtissue along with a portion of the implantable layer of FIG. 12 capturedwithin the staple.

FIG. 14 is a detail view of an implantable layer including a pluralityof foam fragments, in accordance with at least one embodiment of thepresent disclosure.

FIGS. 15A-15F are detail views of implantable layers depicting variousfoam fragments thereof, in accordance with various embodiments of thepresent disclosure.

FIG. 16 is a close-up view of an implantable layer depicting a pluralityof foam fragments, in accordance with at least one embodiment of thepresent disclosure.

FIG. 17 is a graph depicting the release of medicaments from differentfoam fragments, in accordance with at least one embodiment of thepresent disclosure.

FIG. 18 is a perspective view of a portion of an implantable layerdepicting a plurality of arced foam segments thereof, in accordance withat least one embodiment of the present disclosure.

FIG. 19 is a perspective view of a portion of an implantable layerdepicting a plurality of spherical foam segments thereof, in accordancewith at least one embodiment of the present disclosure.

FIG. 20 is a perspective view of a portion of an implantable layerdepicting a plurality of foam segments thereof, in accordance with atleast one embodiment of the present disclosure.

FIG. 21 is a cross-sectional elevation view of a portion of a molddepicting a plurality of foam fragments positioned within a cavity ofthe mold, in accordance with at least one embodiment of the presentdisclosure.

FIG. 22 is a cross-sectional elevation view of the portion of the moldof FIG. 21 depicting the application of heat and pressure to the foamfragments positioned within the cavity of the mold.

FIG. 23 is a detail view of a group of foam fragments within the cavityof the mold of FIG. 21 before the application of heat and pressurethereto.

FIG. 24 is a detail view of the group of foam fragments of FIG. 23 afterthe application of heat and pressure thereto.

FIG. 25 is a schematic of a grinder and a sorter for obtaining foamfragments, in accordance with at least one embodiment of the presentdisclosure.

FIG. 26 is a schematic depicting a range in the size of foam fragmentsfrom the grinder of FIG. 25.

FIG. 27 is a graph depicting the variations in the size of foamfragments from the grinder of FIG. 25.

FIG. 28 is a cross-sectional perspective view of a portion of a molddepicting a lyophilization solution dispersed in a cavity of the mold,and further depicting a plurality of bubbles within the lyophilizationsolution at an initial stage in the lyophilization process, inaccordance with at least one embodiment of the present disclosure.

FIG. 29 is a cross-sectional perspective view of the portion of the moldof FIG. 28, depicting the lyophilization solution dispersed in thecavity of the mold at a secondary stage in the lyophilization process.

FIG. 30 is a cross-sectional perspective view of a portion of a molddepicting a dissolvable insert positioned in a cavity of the mold, inaccordance with at least one embodiment of the present disclosure.

FIG. 31 is a perspective view of a portion of an implantable layerformed in the mold and with the dissolvable insert of FIG. 30 with aportion of the layer removed to reveal tissue ingrowth passages withinthe implantable layer.

FIG. 32 is a cross-sectional perspective view of a portion of a molddepicting a dissolvable insert positioned in a cavity of the mold, inaccordance with at least one embodiment of the present disclosure.

FIG. 33 is a perspective view of a portion of an implantable layerformed in the mold and with the dissolvable insert of FIG. 32 with aportion of the layer removed to reveal tissue ingrowth passages withinthe implantable layer.

FIG. 34 is a perspective view of an implantable layer including aplurality of corrugated layers and with a portion of the implantablelayer removed to reveal portions of the underlying corrugated layers, inaccordance with at least one embodiment of the present disclosure.

FIG. 35 is a perspective view of an implantable layer including aplurality of foam tiers and with a portion of the implantable layerremoved to reveal portions of the underlying foam tiers, in accordancewith at least one embodiment of the present disclosure.

FIG. 36 is a perspective view of an implantable layer including aplurality of fibrous tiers and with a portion of the implantable layerremoved to reveal portions of the underlying fibrous tiers, inaccordance with at least one embodiment of the present disclosure.

FIG. 37 is a cross-sectional perspective view of an implantable layerwith a portion of the implantable layer removed to expose fibersembedded in the implantable layer, in accordance with at least oneembodiment of the present disclosure.

FIG. 38 is a cross-sectional elevation view of a portion of a staplecartridge including an implantable layer and a portion of a stapledepicting the staple in an unfired position and an undeformedconfiguration, in accordance with at least one embodiment of the presentdisclosure.

FIG. 39 is a cross-sectional elevation view of the staple of FIG. 38 ina fired position and a deformed configuration, and further depictingtissue along with a portion of the implantable layer of FIG. 38 capturedwithin the staple.

FIG. 40 is a cross-sectional perspective view of an implantable layer,in accordance with at least one embodiment of the present disclosure.

FIG. 41 is a cross-sectional elevation view of a portion of a mold,depicting a solution being dispersed into a cavity of the mold, inaccordance with at least one embodiment of the present disclosure.

FIG. 42 is a cross-sectional elevation view of a portion of a molddepicting a plurality of loose fibers positioned in a cavity of the moldand a lyophilization solution being dispersed into the cavity, inaccordance with at least one embodiment of the present disclosure.

FIG. 43 is a cross-sectional perspective view of the fibers and thelyophilization solution in the cavity of the mold of FIG. 42 beforeapplication of a lyophilization treatment.

FIG. 44 is a cross-sectional elevation view of an implantable layerformed from the loose fibers and the lyophilization solution in thecavity of the mold of FIG. 42 after application of the lyophilizationtreatment.

FIG. 45 is a cross-sectional elevation view of a portion of a molddepicting a plurality of fibers woven into a three-dimensional mesh andpositioned in the cavity of the mold, and further depicting alyophilization solution being dispersed into the cavity, in accordancewith at least one embodiment of the present disclosure.

FIG. 46 is a cross-sectional elevation view of an implantable layerformed from the woven fibers and the lyophilization solution in thecavity of the mold of FIG. 45 after application of a lyophilizationtreatment.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate various embodiments of the invention, in one form, and suchexemplifications are not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION

The Applicant of the present application owns the following U.S. patentapplications that were filed on even date herewith and which are eachherein incorporated by reference in their respective entireties:

U.S. patent application Ser. No. ______, entitled IMPLANTABLE LAYERS FORA SURGICAL INSTRUMENT; Attorney Docket No. END7550USNP/150078; and

U.S. patent application Ser. No. ______, entitled IMPLANTABLE LAYERS FORA SURGICAL INSTRUMENT; Attorney Docket No. END7550USNP/150079.

The Applicant of the present application also owns the U.S. patentapplications identified below which are each herein incorporated byreference in their respective entireties:

U.S. patent application Ser. No. 12/894,311, entitled SURGICALINSTRUMENTS WITH RECONFIGURABLE SHAFT SEGMENTS; now U.S. Pat. No.8,763,877;

U.S. patent application Ser. No. 12/894,340, entitled SURGICAL STAPLECARTRIDGES SUPPORTING NON-LINEARLY ARRANGED STAPLES AND SURGICALSTAPLING INSTRUMENTS WITH COMMON STAPLE-FORMING POCKETS; now U.S. Pat.No. 8,899,463;

U.S. patent application Ser. No. 12/894,327, entitled JAW CLOSUREARRANGEMENTS FOR SURGICAL INSTRUMENTS; now U.S. Pat. No. 8,978,956;

U.S. patent application Ser. No. 12/894,351, entitled SURGICAL CUTTINGAND FASTENING INSTRUMENTS WITH SEPARATE AND DISTINCT FASTENER DEPLOYMENTAND TISSUE CUTTING SYSTEMS; now U.S. Patent Application Publication No.2012/0080502;

U.S. patent application Ser. No. 12/894,338, entitled IMPLANTABLEFASTENER CARTRIDGE HAVING A NON-UNIFORM ARRANGEMENT; now U.S. Pat. No.8,864,007;

U.S. patent application Ser. No. 12/894,369, entitled IMPLANTABLEFASTENER CARTRIDGE COMPRISING A SUPPORT RETAINER; now U.S. PatentApplication Publication No. 2012/0080344;

U.S. patent application Ser. No. 12/894,312, entitled IMPLANTABLEFASTENER CARTRIDGE COMPRISING MULTIPLE LAYERS; now U.S. Pat. No.8,925,782;

U.S. patent application Ser. No. 12/894,377, entitled SELECTIVELYORIENTABLE IMPLANTABLE FASTENER CARTRIDGE; now U.S. Pat. No. 8,393,514;

U.S. patent application Ser. No. 12/894,339, entitled SURGICAL STAPLINGINSTRUMENT WITH COMPACT ARTICULATION CONTROL ARRANGEMENT; now U.S. Pat.No. 8,840,003;

U.S. patent application Ser. No. 12/894,360, entitled SURGICAL STAPLINGINSTRUMENT WITH A VARIABLE STAPLE FORMING SYSTEM; now U.S. PatentApplication Publication No. 2012/0080484;

U.S. patent application Ser. No. 12/894,322, entitled SURGICAL STAPLINGINSTRUMENT WITH INTERCHANGEABLE STAPLE CARTRIDGE ARRANGEMENTS; now U.S.Pat. No. 8,740,034;

U.S. patent application Ser. No. 12/894,350, entitled SURGICAL STAPLECARTRIDGES WITH DETACHABLE SUPPORT STRUCTURES; now U.S. PatentApplication Publication No. 2012/0080478;

U.S. patent application Ser. No. 12/894,383, entitled IMPLANTABLEFASTENER CARTRIDGE COMPRISING BIOABSORBABLE LAYERS; now U.S. Pat. No.8,752,699;

U.S. patent application Ser. No. 12/894,389, entitled COMPRESSIBLEFASTENER CARTRIDGE; now U.S. Pat. No. 8,740,037;

U.S. patent application Ser. No. 12/894,345, entitled FASTENERSSUPPORTED BY A FASTENER CARTRIDGE SUPPORT; now U.S. Pat. No. 8,783,542;

U.S. patent application Ser. No. 12/894,306, entitled COLLAPSIBLEFASTENER CARTRIDGE; now U.S. Pat. No. 9,044,227;

U.S. patent application Ser. No. 12/894,318, entitled FASTENER SYSTEMCOMPRISING A PLURALITY OF CONNECTED RETENTION MATRIX ELEMENTS; now U.S.Pat. No. 8,814,024;

U.S. patent application Ser. No. 12/894,330, entitled FASTENER SYSTEMCOMPRISING A RETENTION MATRIX AND AN ALIGNMENT MATRIX; now U.S. Pat. No.8,757,465;

U.S. patent application Ser. No. 12/894,361, entitled FASTENER SYSTEMCOMPRISING A RETENTION MATRIX; now U.S. Pat. No. 8,529,600;

U.S. patent application Ser. No. 12/894,367, entitled FASTENINGINSTRUMENT FOR DEPLOYING A FASTENER SYSTEM COMPRISING A RETENTIONMATRIX; now U.S. Pat. No. 9,033,203;

U.S. patent application Ser. No. 12/894,388, entitled FASTENER SYSTEMCOMPRISING A RETENTION MATRIX AND A COVER; now U.S. Pat. No. 8,474,677;

U.S. patent application Ser. No. 12/894,376, entitled FASTENER SYSTEMCOMPRISING A PLURALITY OF FASTENER CARTRIDGES; now U.S. Pat. No.9,044,228;

U.S. patent application Ser. No. 13/097,865, entitled SURGICAL STAPLERANVIL COMPRISING A PLURALITY OF FORMING POCKETS; now U.S. PatentApplication Publication No. 2012/0080488;

U.S. patent application Ser. No. 13/097,936, entitled TISSUE THICKNESSCOMPENSATOR FOR A SURGICAL STAPLER; now U.S. Pat. No. 8,657,176;

U.S. patent application Ser. No. 13/097,954, entitled STAPLE CARTRIDGECOMPRISING A VARIABLE THICKNESS COMPRESSIBLE PORTION; now U.S. PatentApplication Publication No. 2012/0080340;

U.S. patent application Ser. No. 13/097,856, entitled STAPLE CARTRIDGECOMPRISING STAPLES POSITIONED WITHIN A COMPRESSIBLE PORTION THEREOF; nowU.S. Patent Application Publication No. 2012/0080336;

U.S. patent application Ser. No. 13/097,928, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING DETACHABLE PORTIONS; now U.S. Pat. No. 8,746,535;

U.S. patent application Ser. No. 13/097,891, entitled TISSUE THICKNESSCOMPENSATOR FOR A SURGICAL STAPLER COMPRISING AN ADJUSTABLE ANVIL; nowU.S. Pat. No. 8,864,009;

U.S. patent application Ser. No. 13/097,948, entitled STAPLE CARTRIDGECOMPRISING AN ADJUSTABLE DISTAL PORTION; now U.S. Pat. No. 8,978,954;

U.S. patent application Ser. No. 13/097,907, entitled COMPRESSIBLESTAPLE CARTRIDGE ASSEMBLY; now U.S. Patent Application Publication No.2012/0080338;

U.S. patent application Ser. No. 13/097,861, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING PORTIONS HAVING DIFFERENT PROPERTIES; now U.S.Patent Application Publication No. 2012/0080337;

U.S. patent application Ser. No. 13/097,869, entitled STAPLE CARTRIDGELOADING ASSEMBLY; now U.S. Pat. No. 8,857,694;

U.S. patent application Ser. No. 13/097,917, entitled COMPRESSIBLESTAPLE CARTRIDGE COMPRISING ALIGNMENT MEMBERS; now U.S. Pat. No.8,777,004;

U.S. patent application Ser. No. 13/097,873, entitled STAPLE CARTRIDGECOMPRISING A RELEASABLE PORTION; now U.S. Pat. No. 8,740,038;

U.S. patent application Ser. No. 13/097,938, entitled STAPLE CARTRIDGECOMPRISING COMPRESSIBLE DISTORTION RESISTANT COMPONENTS; now U.S. Pat.No. 9,016,542;

U.S. patent application Ser. No. 13/097,924, entitled STAPLE CARTRIDGECOMPRISING A TISSUE THICKNESS COMPENSATOR; now U.S. Patent ApplicationPublication No. 2012/0083835;

U.S. patent application Ser. No. 13/242,029, entitled SURGICAL STAPLERWITH FLOATING ANVIL; now U.S. Pat. No. 8,893,949;

U.S. patent application Ser. No. 13/242,066, entitled CURVED ENDEFFECTOR FOR A STAPLING INSTRUMENT; now U.S. Patent ApplicationPublication No. 2012/0080498;

U.S. patent application Ser. No. 13/242,086, entitled STAPLE CARTRIDGEINCLUDING COLLAPSIBLE DECK; now U.S. Pat. No. 9,055,941;

U.S. patent application Ser. No. 13/241,912, entitled STAPLE CARTRIDGEINCLUDING COLLAPSIBLE DECK ARRANGEMENT; now U.S. Pat. No. 9,050,084;

U.S. patent application Ser. No. 13/241,922, entitled SURGICAL STAPLERWITH STATIONARY STAPLE DRIVERS; now U.S. Patent Application PublicationNo. 2013/0075449;

U.S. patent application Ser. No. 13/241,637, entitled SURGICALINSTRUMENT WITH TRIGGER ASSEMBLY FOR GENERATING MULTIPLE ACTUATIONMOTIONS; now U.S. Pat. No. 8,789,741;

U.S. patent application Ser. No. 13/241,629, entitled SURGICALINSTRUMENT WITH SELECTIVELY ARTICULATABLE END EFFECTOR; now U.S. PatentApplication Publication No. 2012/0074200;

U.S. patent application Ser. No. 13/433,096, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING A PLURALITY OF CAPSULES; now U.S. PatentApplication Publication No. 2012/0241496;

U.S. patent application Ser. No. 13/433,103, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING A PLURALITY OF LAYERS; now U.S. PatentApplication Publication No. 2012/0241498;

U.S. patent application Ser. No. 13/433,098, entitled EXPANDABLE TISSUETHICKNESS COMPENSATOR; now U.S. Patent Application Publication No.2012/0241491;

U.S. patent application Ser. No. 13/433,102, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING A RESERVOIR; now U.S. Patent ApplicationPublication No. 2012/0241497;

U.S. patent application Ser. No. 13/433,114, entitled RETAINER ASSEMBLYINCLUDING A TISSUE THICKNESS COMPENSATOR; now U.S. Patent ApplicationPublication No. 2012/0241499;

U.S. patent application Ser. No. 13/433,136, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING AT LEAST ONE MEDICAMENT; now U.S. PatentApplication Publication No. 2012/0241492;

U.S. patent application Ser. No. 13/433,141, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING CONTROLLED RELEASE AND EXPANSION; now U.S. PatentApplication Publication No. 2012/0241493;

U.S. patent application Ser. No. 13/433,144, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING FIBERS TO PRODUCE A RESILIENT LOAD; now U.S.Patent Application Publication No. 2012/0241500;

U.S. patent application Ser. No. 13/433,148, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING STRUCTURE TO PRODUCE A RESILIENT LOAD; now U.S.Patent Application Publication No. 2012/0241501;

U.S. patent application Ser. No. 13/433,155, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING RESILIENT MEMBERS; now U.S. Patent ApplicationPublication No. 2012/0241502;

U.S. patent application Ser. No. 13/433,163, entitled METHODS FORFORMING TISSUE THICKNESS COMPENSATOR ARRANGEMENTS FOR SURGICAL STAPLERS;now U.S. Patent Application Publication No. 2012/0248169;

U.S. patent application Ser. No. 13/433,167, entitled TISSUE THICKNESSCOMPENSATORS; now U.S. Patent Application Publication No. 2012/0241503;

U.S. patent application Ser. No. 13/433,175, entitled LAYERED TISSUETHICKNESS COMPENSATOR; now U.S. Patent Application Publication No.2012/0253298;

U.S. patent application Ser. No. 13/433,179, entitled TISSUE THICKNESSCOMPENSATORS FOR CIRCULAR SURGICAL STAPLERS; now U.S. Patent ApplicationPublication No. 2012/0241505;

U.S. patent application Ser. No. 13/763,028, entitled ADHESIVE FILMLAMINATE; now U.S. Patent Application Publication No. 2013/0146643;

U.S. patent application Ser. No. 13/433,115, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING CAPSULES DEFINING A LOW PRESSURE ENVIRONMENT; nowU.S. Patent Application Publication No. 2013/0256372;

U.S. patent application Ser. No. 13/433,118, entitled TISSUE THICKNESSCOMPENSATOR COMPRISED OF A PLURALITY OF MATERIALS; now U.S. PatentApplication Publication No. 2013/0256365;

U.S. patent application Ser. No. 13/433,135, entitled MOVABLE MEMBER FORUSE WITH A TISSUE THICKNESS COMPENSATOR; now U.S. Patent ApplicationPublication No. 2013/0256382;

U.S. patent application Ser. No. 13/433,140, entitled TISSUE THICKNESSCOMPENSATOR AND METHOD FOR MAKING THE SAME; now U.S. Patent ApplicationPublication No. 2013/0256368;

U.S. patent application Ser. No. 13/433,129, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING A PLURALITY OF MEDICAMENTS; now U.S. PatentApplication Publication No. 2013/0256367;

U.S. patent application Ser. No. 11/216,562, entitled STAPLE CARTRIDGESFOR FORMING STAPLES HAVING DIFFERING FORMED STAPLE HEIGHTS, now U.S.Pat. No. 7,669,746;

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U.S. patent application Ser. No. 11/711,979, entitled SURGICAL STAPLINGDEVICES THAT PRODUCE FORMED STAPLES HAVING DIFFERENT LENGTHS, now U.S.Pat. No. 8,317,070;

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U.S. patent application Ser. No. 11/711,977, entitled SURGICAL STAPLINGDEVICE WITH STAPLE DRIVER THAT SUPPORTS MULTIPLE WIRE DIAMETER STAPLES,now U.S. Pat. No. 7,673,781;

U.S. patent application Ser. No. 11/712,315, entitled SURGICAL STAPLINGDEVICE WITH MULTIPLE STACKED ACTUATOR WEDGE CAMS FOR DRIVING STAPLEDRIVERS, now U.S. Pat. No. 7,500,979;

U.S. patent application Ser. No. 12/038,939, entitled STAPLE CARTRIDGESFOR FORMING STAPLES HAVING DIFFERING FORMED STAPLE HEIGHTS, now U.S.Pat. No. 7,934,630;

U.S. patent application Ser. No. 13/020,263, entitled SURGICAL STAPLINGSYSTEMS THAT PRODUCE FORMED STAPLES HAVING DIFFERENT LENGTHS, now U.S.Pat. No. 8,636,187;

U.S. patent application Ser. No. 13/118,278, entitledROBOTICALLY-CONTROLLED SURGICAL STAPLING DEVICES THAT PRODUCE FORMEDSTAPLES HAVING DIFFERENT LENGTHS, now U.S. Patent ApplicationPublication No. 2011/0290851;

U.S. patent application Ser. No. 13/369,629, entitledROBOTICALLY-CONTROLLED CABLE-BASED SURGICAL END EFFECTORS, now U.S. Pat.No. 8,800,838;

U.S. patent application Ser. No. 12/695,359, entitled SURGICAL STAPLINGDEVICES FOR FORMING STAPLES WITH DIFFERENT FORMED HEIGHTS, now U.S. Pat.No. 8,464,923;

U.S. patent application Ser. No. 13/072,923, entitled STAPLE CARTRIDGESFOR FORMING STAPLES HAVING DIFFERING FORMED STAPLE HEIGHTS, now U.S.Pat. No. 8,567,656;

U.S. patent application Ser. No. 13/766,325, entitled LAYER OF MATERIALFOR A SURGICAL END EFFECTOR; now U.S. Patent Application Publication No.2013/0256380;

U.S. patent application Ser. No. 13/763,078, entitled ANVIL LAYERATTACHED TO A PROXIMAL END OF AN END EFFECTOR; now U.S. PatentApplication Publication No. 2013/0256383;

U.S. patent application Ser. No. 13/763,094, entitled LAYER COMPRISINGDEPLOYABLE ATTACHMENT MEMBERS; now U.S. Patent Application PublicationNo. 2013/0256377;

U.S. patent application Ser. No. 13/763,106, entitled END EFFECTORCOMPRISING A DISTAL TISSUE ABUTMENT MEMBER; now U.S. Patent ApplicationPublication No. 2013/0256378;

U.S. patent application Ser. No. 13/433,147, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING CHANNELS; now U.S. Patent Application PublicationNo. 2013/0256369;

U.S. patent application Ser. No. 13/763,112, entitled SURGICAL STAPLINGCARTRIDGE WITH LAYER RETENTION FEATURES; now U.S. Patent ApplicationPublication No. 2013/0256379;

U.S. patent application Ser. No. 13/763,035, entitled ACTUATOR FORRELEASING A TISSUE THICKNESS COMPENSATOR FROM A FASTENER CARTRIDGE; nowU.S. Patent Application Publication No. 2013/0214030;

U.S. patent application Ser. No. 13/763,042, entitled RELEASABLE TISSUETHICKNESS COMPENSATOR AND FASTENER CARTRIDGE HAVING THE SAME; now U.S.Patent Application Publication No. 2013/0221063;

U.S. patent application Ser. No. 13/763,048, entitled FASTENER CARTRIDGECOMPRISING A RELEASABLE TISSUE THICKNESS COMPENSATOR; now U.S. PatentApplication Publication No. 2013/0221064;

U.S. patent application Ser. No. 13/763,054, entitled FASTENER CARTRIDGECOMPRISING A CUTTING MEMBER FOR RELEASING A TISSUE THICKNESSCOMPENSATOR; now U.S. Patent Application Publication No. 2014/0097227;

U.S. patent application Ser. No. 13/763,065, entitled FASTENER CARTRIDGECOMPRISING A RELEASABLY ATTACHED TISSUE THICKNESS COMPENSATOR; now U.S.Patent Application Publication No. 2013/0221065;

U.S. patent application Ser. No. 13/763,021, entitled STAPLE CARTRIDGECOMPRISING A RELEASABLE COVER; now U.S. Patent Application PublicationNo. 2014/0224686;

U.S. patent application Ser. No. 13/763,078, entitled ANVIL LAYERATTACHED TO A PROXIMAL END OF AN END EFFECTOR; now U.S. PatentApplication Publication No. 2013/0256383;

U.S. patent application Ser. No. 13/763,095, entitled LAYER ARRANGEMENTSFOR SURGICAL STAPLE CARTRIDGES; now U.S. Patent Application PublicationNo. 2013/0161374;

U.S. patent application Ser. No. 13/763,147, entitled IMPLANTABLEARRANGEMENTS FOR SURGICAL STAPLE CARTRIDGES; now U.S. Patent ApplicationPublication No. 2013/0153636;

U.S. patent application Ser. No. 13/763,192, entitled MULTIPLE THICKNESSIMPLANTABLE LAYERS FOR SURGICAL STAPLING DEVICES; now U.S. PatentApplication Publication No. 2013/0146642;

U.S. patent application Ser. No. 13/763,161, entitled RELEASABLE LAYEROF MATERIAL AND SURGICAL END EFFECTOR HAVING THE SAME; now U.S. PatentApplication Publication No. 2013/0153641;

U.S. patent application Ser. No. 13/763,177, entitled ACTUATOR FORRELEASING A LAYER OF MATERIAL FROM A SURGICAL END EFFECTOR; now U.S.Patent Application Publication No. 2013/0146641;

U.S. patent application Ser. No. 13/763,037, entitled STAPLE CARTRIDGECOMPRISING A COMPRESSIBLE PORTION; now U.S. Patent ApplicationPublication No. 2014/0224857;

U.S. patent application Ser. No. 13/433,126, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING TISSUE INGROWTH FEATURES; now U.S. PatentApplication Publication No. 2013/0256366;

U.S. patent application Ser. No. 13/433,132, entitled DEVICES ANDMETHODS FOR ATTACHING TISSUE THICKNESS COMPENSATING MATERIALS TOSURGICAL STAPLING INSTRUMENTS; now U.S. Patent Application PublicationNo. 2013/0256373;

U.S. patent application Ser. No. 13/851,703, entitled FASTENER CARTRIDGECOMPRISING A TISSUE THICKNESS COMPENSATOR INCLUDING OPENINGS THEREIN;now U.S. Patent Application Publication No. 2014/0291382;

U.S. patent application Ser. No. 13/851,676, entitled TISSUE THICKNESSCOMPENSATOR COMPRISING A CUTTING MEMBER PATH; now U.S. PatentApplication Publication No. 2014/0291379;

U.S. patent application Ser. No. 13/851,693, entitled FASTENER CARTRIDGEASSEMBLIES; now U.S. Patent Application Publication No. 2014/0291381;

U.S. patent application Ser. No. 13/851,684, entitled FASTENER CARTRIDGECOMPRISING A TISSUE THICKNESS COMPENSATOR AND A GAP SETTING ELEMENT; nowU.S. Patent Application Publication No. 2014/0291380;

U.S. patent application Ser. No. 14/187,387, entitled STAPLE CARTRIDGEINCLUDING A BARBED STAPLE, now U.S. Patent Application Publication No.2014/0166724;

U.S. patent application Ser. No. 14/187,395, entitled STAPLE CARTRIDGEINCLUDING A BARBED STAPLE, now U.S. Patent Application Publication No.2014/0166725;

U.S. patent application Ser. No. 14/187,400, entitled STAPLE CARTRIDGEINCLUDING A BARBED STAPLE, now U.S. Patent Application Publication No.2014/0166726;

U.S. patent application Ser. No. 14/187,383, entitled IMPLANTABLE LAYERSAND METHODS FOR ALTERING IMPLANTABLE LAYERS FOR USE WITH SURGICALFASTENING INSTRUMENTS;

U.S. patent application Ser. No. 14/187,386, entitled IMPLANTABLE LAYERSAND METHODS FOR ALTERING ONE OR MORE PROPERTIES OF IMPLANTABLE LAYERSFOR USE WITH FASTENING INSTRUMENTS;

U.S. patent application Ser. No. 14/187,390, entitled IMPLANTABLE LAYERSAND METHODS FOR MODIFYING THE SHAPE OF THE IMPLANTABLE LAYERS FOR USEWITH A SURGICAL FASTENING INSTRUMENT;

U.S. patent application Ser. No. 14/187,389, entitled IMPLANTABLE LAYERASSEMBLIES;

U.S. patent application Ser. No. 14/187,385, entitled IMPLANTABLE LAYERSCOMPRISING A PRESSED REGION; and

U.S. patent application Ser. No. 14/187,384, entitled FASTENING SYSTEMCOMPRISING A FIRING MEMBER LOCKOUT.

Numerous specific details are set forth to provide a thoroughunderstanding of the overall structure, function, manufacture, and useof the embodiments as described in the specification and illustrated inthe accompanying drawings. Well-known operations, components, andelements have not been described in detail so as not to obscure theembodiments described in the specification. The reader will understandthat the embodiments described and illustrated herein are non-limitingexamples, and thus it can be appreciated that the specific structuraland functional details disclosed herein may be representative andillustrative. Variations and changes thereto may be made withoutdeparting from the scope of the claims.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a surgicalsystem, device, or apparatus that “comprises,” “has,” “includes” or“contains” one or more elements possesses those one or more elements,but is not limited to possessing only those one or more elements.Likewise, an element of a system, device, or apparatus that “comprises,”“has,” “includes” or “contains” one or more features possesses those oneor more features, but is not limited to possessing only those one ormore features.

The terms “proximal” and “distal” are used herein with reference to aclinician manipulating the handle portion of the surgical instrument.The term “proximal” referring to the portion closest to the clinicianand the term “distal” referring to the portion located away from theclinician. It will be further appreciated that, for convenience andclarity, spatial terms such as “vertical”, “horizontal”, “up”, and“down” may be used herein with respect to the drawings. However,surgical instruments are used in many orientations and positions, andthese terms are not intended to be limiting and/or absolute.

Various exemplary devices and methods are provided for performinglaparoscopic and minimally invasive surgical procedures. However, thereader will readily appreciate that the various methods and devicesdisclosed herein can be used in numerous surgical procedures andapplications including, for example, in connection with open surgicalprocedures. As the present Detailed Description proceeds, the readerwill further appreciate that the various instruments disclosed hereincan be inserted into a body in any way, such as through a naturalorifice, through an incision or puncture hole formed in tissue, etc. Theworking portions or end effector portions of the instruments can beinserted directly into a patient's body or can be inserted through anaccess device that has a working channel through which an end effectorand elongated shaft of a surgical instrument can be advanced.

A surgical stapling system can comprise a shaft and an end effectorextending from the shaft. The end effector comprises a first jaw and asecond jaw. The first jaw comprises a staple cartridge. The staplecartridge is insertable into and removable from the first jaw; however,other embodiments are envisioned in which a staple cartridge is notremovable from, or at least readily replaceable from, the first jaw. Thesecond jaw comprises an anvil configured to deform staples ejected fromthe staple cartridge. The second jaw is pivotable relative to the firstjaw about a closure axis; however, other embodiments are envisioned inwhich the first jaw is pivotable relative to the second jaw. Thesurgical stapling system further comprises an articulation jointconfigured to permit the end effector to be rotated, or articulated,relative to the shaft. The end effector is rotatable about anarticulation axis extending through the articulation joint. Otherembodiments are envisioned which do not include an articulation joint.

The staple cartridge comprises a cartridge body. The cartridge bodyincludes a proximal end, a distal end, and a deck extending between theproximal end and the distal end. In use, the staple cartridge ispositioned on a first side of the tissue to be stapled and the anvil ispositioned on a second side of the tissue. The anvil is moved toward thestaple cartridge to compress and clamp the tissue against the deck.Thereafter, staples removably stored in the cartridge body can bedeployed into the tissue. The cartridge body includes staple cavitiesdefined therein wherein staples are removably stored in the staplecavities. The staple cavities are arranged in six longitudinal rows.Three rows of staple cavities are positioned on a first side of alongitudinal slot and three rows of staple cavities are positioned on asecond side of the longitudinal slot. Other arrangements of staplecavities and staples may be possible.

The staples are supported by staple drivers in the cartridge body. Thedrivers are movable between a first, or unfired position, and a second,or fired, position to eject the staples from the staple cavities. Thedrivers are retained in the cartridge body by a retainer which extendsaround the bottom of the cartridge body and includes resilient membersconfigured to grip the cartridge body and hold the retainer to thecartridge body. The drivers are movable between their unfired positionsand their fired positions by a sled. The sled is movable between aproximal position adjacent the proximal end and a distal positionadjacent the distal end. The sled comprises a plurality of rampedsurfaces configured to slide under the drivers and lift the drivers, andthe staples supported thereon, toward the anvil.

Further to the above, the sled is moved distally by a firing member. Thefiring member is configured to contact the sled and push the sled towardthe distal end. The longitudinal slot defined in the cartridge body isconfigured to receive the firing member. The anvil also includes a slotconfigured to receive the firing member. The firing member furthercomprises a first cam which engages the first jaw and a second cam whichengages the second jaw. As the firing member is advanced distally, thefirst cam and the second cam can control the distance, or tissue gap,between the deck of the staple cartridge and the anvil. The firingmember also comprises a knife configured to incise the tissue capturedintermediate the staple cartridge and the anvil. It is desirable for theknife to be positioned at least partially proximal to the rampedsurfaces such that the staples are ejected ahead of the knife.

The staple cartridge can also include an implantable layer. Theimplantable layer is configured to be captured within a staple alongwith tissue when the staple is deployed by the corresponding driver. Theimplantable layer can comprise a buttress, a tissue thicknesscompensator, and/or other adjunct material. A tissue thicknesscompensator is configured to compensate for variations in tissueproperties, such as variations in the thickness of tissue, for example,along a staple line. A tissue thickness compensator can be compressibleand resilient. In use, a tissue thickness compensator prevents or limitsthe over-compression of stapled tissue while facilitating adequatetissue compression within and between staples.

The implantable layer of a staple cartridge can be releasably secured tothe body of the staple cartridge. For example, the implantable layer canbe releasably secured to the deck of the staple cartridge with areleasable adhesive, at least one attachment tab, and/or otherattachment features. Additionally or alternatively, an implantable layercan be releasably secured to the first jaw or the second jaw. Animplantable layer can be positioned on the cartridge-side of an endeffector and/or the anvil-side of the end effector, for example.

An implantable layer can be configured to promote tissue ingrowth. Invarious instances, it is desirable to promote the ingrowth of tissueinto an implantable layer to promote the healing of the treated tissue(e.g. stapled and/or incised tissue) and/or to accelerate the patient'srecovery. More specifically, the ingrowth of tissue into an implantablelayer may reduce the incidence, extent, and/or duration of inflammationat the surgical site. Tissue ingrowth into and/or around the implantablelayer may manage the spread of infections at the surgical site, forexample. The ingrowth of blood vessels, especially white blood cells,for example, into and/or around the implantable layer may fightinfections in and/or around the implantable layer and the adjacenttissue. Tissue ingrowth may also encourage the acceptance of foreignmatter (e.g. the implantable layer and the staples) by the patient'sbody and may reduce the likelihood of the patient's body rejecting theforeign matter. Rejection of foreign matter may cause infection and/orinflammation at the surgical site.

An implantable layer having insufficient inlets and/or passages from theouter surface(s) of the implantable layer toward an inner portion of thelayer may impede the ingrowth of tissue into the inner portion. In suchinstances, the tissue may be unable to obtain a foothold or grip on theimplantable layer and/or tissue growth into the implantable layer may berestricted. The tissue may be unable to gain traction along and/oraround the outer surface of the implantable layer, and thus, into theinner portion thereof. Even when the inner portion of the implantablelayer comprises an adequate porosity and/or density to permit tissueingrowth, the ingrowth of tissue may be obstructed if the outer surface,shell, or skin of the implantable layer comprises insufficient inletsand/or footholds for tissue ingrowth. For example, various foammaterials, such as foam comprising a closed cellular structure and/orlyophilized foam, for example, can include a denser, less porous outerportion. Additionally or alternatively, various foam materials can behydrophobic and/or comprise an outer surface that is substantiallysmooth and/or flat and, thus, is unconducive to cell adhesion. In suchinstances, the ingrowth of tissue into the inner portion of theimplantable layer may be thwarted by the properties of the outer portionof the implantable layer.

In various instances, an implantable layer can include at least onetissue ingrowth passage through which tissue can be encouraged to growand propagate. Such a tissue ingrowth passage can extend from an outersurface of the implantable layer toward and/or into an inner portion ofthe implantable layer. For example, the tissue ingrowth passage caninclude an inlet along a surface or face of the implantable layer.Additionally or alternatively, an implantable layer can include asurface treatment which can promote cell adhesion and/or cell motilityalong the surface and/or into the implantable layer. In certaininstances, the material comprising the implantable layer can be degradedand/or deteriorated prior to the implantation of the implantable layer.An implantable layer comprising at least one ingrowth passage, surfacetreatment, and/or expedited degradation profile can be configured topromote tissue ingrowth. Additionally, the addition of a tissue ingrowthpassage reduces the volume of the implantable layer, which may furtherprevent or reduce the likelihood of the patient's body rejecting theforeign layer implanted therein.

Referring to FIG. 1, a portion of an implantable layer 100 is depicted.The implantable layer 100 comprises a tissue thickness compensator. Inother embodiments, the implantable layer 100 comprises a piece ofbuttress material. The implantable layer 100 includes a body 102 havingan inner portion 106 and an outer portion 108. The outer portion 108surrounds the inner portion 106 such that the inner portion 106 isdefined within the boundary of the outer portion 108. The outer portion108 includes a plurality of faces or sides 104, which define theperimeter of the body 102. In various instances, the body 102 of theimplantable layer 100 comprises a rectangular prism having six facesincluding a first face 104 a. In other instances, the body 102 cancomprise a triangular prism or another three-dimensional shape. In thedepicted embodiment, the first face 104 a corresponds to atissue-contacting surface of the implantable layer 100. In otherinstances, the first face 104 a can correspond to a deck-contactingsurface or a sidewall of the body 102.

The body 102 of the implantable layer 100 is a porous body. For example,the body 102 comprises a piece of foam having a plurality of pores 110defined therein. In various instances, the body 102 is a piece oflyophilized foam. The body 102 comprises an open cellular structure. Forexample, a pore 110 a is adjacent to the first face 104 a of the body102 and the boundary of the pore 110 a defines an outer surface of thebody 102. Open cell pores, such as the pore 110 a, for example, canprovide a tissue ingrowth inlet and/or a foothold for tissue ingrowth.In other embodiments, the body 102 can comprise a closed-cell structure.In such instances, the pores 110 can be positioned entirely within thebody 102. Closed-cell pores are not open to an outer surface or face 104of the body 102.

The body 102 also includes a plurality of tissue ingrowth passages 120.The passages 120 extend from the outer portion 108 of the body 102toward the inner portion 106 of the body 102. For example, at least onepassage 120 extends from the first face 104 a of the outer portion 108toward the inner portion 106. At least one passage 120 extends throughthe body 102. For example, a first passage 120 a extends from the firstface 104 a to the opposing face 104 of the body 102. At least onepassage 120 terminates within the inner portion 106 of the body 102, andat least two passages 120 transect or cross within the body 102.Additionally, at least one passage 120 transects and/or passes throughat least one pore 110 in the body 102.

The various passages 120 are oriented at different angles within thebody 102 and propagate in different directions within the body 102. Forexample, the first passage 120 a is angularly-oriented relative to asecond passage 102 b and the first passage 120 a transects the secondpassage 120 b in the inner portion 106 of the body 102. The variouspassages 120 into and/or through the body 102 are configured to providea pathway for tissue to grow into the implantable layer 100. Forexample, at least one passage 120 can extend from the tissue-contactingsurface 104 a of the implantable layer 100. In at least one instance,the varied orientation of the passages 120 may promote the integrationof the implantable layer 100 into the surrounding tissue.

Referring primarily now to FIG. 2, a portion of a staple cartridge 250is shown. The staple cartridge 250 includes a cartridge body 252 havinga deck 256. A plurality of staple cavities are defined in the cartridgebody 252, and each staple cavity comprises an opening in the deck 256.For example, a staple cavity 254 is defined in the cartridge body 252.The staple cartridge 250 further includes a plurality of staples. Forexample, a staple 260 is positioned in the staple cavity 254. The staplecartridge 250 includes an implantable layer 200, which is positionedadjacent to the deck 256 of the cartridge body 252. The implantablelayer 200 extends over the staple cavity openings in the deck 256. Theimplantable layer 200 can be releasably positioned relative to the deck256.

Referring to FIGS. 2 and 3, the implantable layer 200 comprises a tissuethickness compensator. The implantable layer 200 includes a plurality ofpores 210 and a plurality of tissue ingrowth passages 220. Theimplantable layer 200 also includes a first face 204 a and a second face204 b. The first face 204 a comprises a tissue-contacting surface. Forexample, during a stapling operation, tissue T is positioned against andcompressed against the first face 204 a of the implantable layer. Thesecond face 204 b is opposite to the first face 204 a. Moreparticularly, in the orientation depicted in FIG. 2, the first face 204a comprises a top surface of the implantable layer 200, and the secondface 204 b comprises a bottom surface of the implantable layer 200. Thesecond face 204 b comprises a deck-contacting surface. At least one ofthe passages 220 in the implantable layer 200 extends between theopposing first face 204 a and second face 204 b. Referring to theembodiment of FIGS. 2 and 3, a plurality of passages 220 extend betweenthe first face 204 a and the second face 204 b. Such passages 220provide pathways for tissue ingrowth between opposing sides of theimplantable layer (e.g. between the top surface and the bottom surface).

During a stapling operation, tissue T is captured within the staple 260along with a portion of the implantable layer 200. The tissue T and theimplantable layer 200 are compressed within the fired and deformedstaple 260 (FIG. 3). As depicted in FIG. 3, the height of the compressedimplantable layer 200 varies within the formed staple 260 in response tovarious properties of the adjacent tissue T. For example, theimplantable layer 200 is configured to assume a greater height where thecaptured tissue T is thinner and is configured to assume a lesser heightwhere the captured tissue T is thicker. The reader will furtherappreciate that the height of the compressed implantable layer 200 canalso vary from staple to staple in a staple line and/or in the unstapledregions between adjacent staples in the staple line in response tovarious properties of the tissue T.

When the implantable layer 200 is compressed during a staplingoperation, the first face 204 a of the implantable layer 200 iscompressed toward the second face 204 b of the implantable layer 200.For example, the implantable layer 200 is compressed along an axis ofcompression A (FIG. 3), which is perpendicular, or substantiallyperpendicular, to the first face 204 a and the second face 204 b. Insuch instances, various tissue ingrowth passages 220 in the implantablelayer 200 are configured to remain open and/or substantiallyunobstructed when the implantable layer 200 is compressed. For example,the tissue ingrowth passages 220 parallel to and/or substantiallyparallel to the axis of compression A remain substantially unobstructedwhen the implantable layer 200 has been compressed along the axis ofcompression A. Moreover, angled passages 220 extending between the firstface 204 a and the second face 204 b and having a sufficient verticalvector component (e.g. a significant vector component aligned with theaxis of compression A) also remain substantially unobstructed. Dependingon the amount of compression, tissue ingrowth passages 220 that areperpendicular, or substantially perpendicular, to the axis ofcompression A can be closed and/or obstructed when the implantable layer200 is compressed within a staple 260.

In various instances, tissue ingrowth passages, such as the passages 120in the implantable layer 100 and/or the passages 220 in the implantablelayer 200, for example, comprise a diameter that is greater than 125 μm(approximately 0.005″) and/or less than the diameter of a staple leg. Incertain instances, a staple leg can have a diameter betweenapproximately 0.005″ and approximately 0.015″, for example. In at leastone instance, a staple leg can have a diameter between approximately0.007″ and approximately 0.010″, for example. In certain instances,tissue ingrowth passages can be less than or equal to 125 μm or greaterthan or equal to the diameter of a staple leg. In various instances, thediameter of the tissue ingrowth passages can be greater than thediameter of the pores defined in the implantable layer. For example, thediameter of a tissue ingrowth passage through an implantable layer canbe at least an order of magnitude greater than the diameter of at leastone pore in the implantable layer. The addition of the tissue ingrowthpassages 120 and 220 are configured not to affect the compressiveproperties and/or resiliency of the implantable layer 100 and 200,respectively.

Tissue ingrowth passages, such as the passages 120 in the implantablelayer 100 and the passages 220 in the implantable layer 200, forexample, can be formed in a variety of ways. In various instances,tissue ingrowth passages can be integrally formed with the implantablelayer. In other instances, tissue ingrowth passages can be added to apreformed implantable layer. For example, a preformed implantable layercan be altered to remove and/or destroy portions thereof to form tissueingrowth passages therethrough.

Referring primarily to FIG. 4, an implantable layer 300 is depicted. Theimplantable layer 300 comprises a tissue thickness compensator. Theimplantable layer 300 includes a body 302 having a plurality of pores310 and a plurality of tissue ingrowth passages 320 defined therein. Thepassages 320 can be formed in a variety of ways. For example, thepassages 320 can be mechanically punched into the body 302 of theimplantable layer 300. More particularly, at least one punch 325 can bepressed and/or poked through the implantable layer 300 to form thetissue ingrowth passages 320. Referring to the embodiment depicted inFIG. 4, a plurality of punches 325 are configured to form the tissueingrowth passages 320 in the body 302. The punches 325 form tissueingrowth passages 320 that extend in a plurality of differentorientations and initiate from different faces 304 of the implantablebody 302. In various instances, the punches 325 can comprise differentdiameters and/or different cross-sectional shapes such that tissueingrowth passages 320 of different diameters and/or differentcross-sectional shapes are formed in the body 302.

In certain instances, a punch 325 can comprise a blunt end for cuttingand/or punching through the body 302. In other instances, the punch 325can comprise a pin and/or needle having a tapered, pointed end. A punchfor forming the passages 320 can comprise various cross-sectionalgeometries. In at least one instance, a punch can comprise a polygonalcross-sectional geometry, such as a triangle, square, rectangle,hexagon, or other polygon, for example. Passages comprising polygonalcross-sectional boundaries, such as those formed from a square punch,for example, may provide a less hospitable and/or inhospitableenvironment for infections to take hold and spread. For example,macrophages and/or multi-nucleated giant cells may prefer passageshaving a circular, contoured, and/or scalloped cross-sectional shape.

In other instances, tissue ingrowth passages in an implantable layer canbe drilled, ultrasonically tooled, and/or formed by water jets and/orlasers. For laser drilled passages, the type and energy of the laser canbe selected to limit and/or reduce melting and/or deformation of thebody adjacent to the laser-drilled tissue ingrowth passage. In variousinstances, lasers can be used to drill staple leg openings into thebody, and such lasers can be further utilized to form tissue ingrowthpassages transverse to and/or offset from the staple leg openings. Thetissue ingrowth passages formed by the lasers can be narrower than thestaple leg openings formed by the lasers. Additionally or alternatively,lasers can also be employed to add texture and/or cutaways on thesurface of an implantable layer. For example, lasers can create elongatecutaways in the body of an implantable layer. Such elongate cutaways canbe positioned intermediate at least two adjacent rows of staplecavities, for example. In various instances, cutaways between rows ofstaple cavities may further promote the ingrowth of tissue intermediateadjacent rows of staple cavities. Lasers can also form an interlockingand/or crossing array of grooves on the surface of the implantable layerto improve cell adhesion and traction.

In still other instances, tissue ingrowth passages can be molded intothe body of the implantable layer. For example, the body can be moldedaround a plurality of removable mold inserts that form channels and/ortunnels at least partially through the body of the implantable layer.Additionally or alternatively, dissolvable material can be molded intothe body of the implantable layer during the molding process. Suchmaterial can be dissolved prior to the stapling operation leavingingrowth passages in its place. Such material could also be dissolvedafter the stapling operation leaving ingrowth passages in its place.Various insert-molding processes for creating tissue ingrowth passagesare further described herein.

Referring now to FIG. 5, a portion of an implantable layer 400 isdepicted. The implantable layer 400 comprises a tissue thicknesscompensator. The implantable layer 400 includes a body 402 having aplurality of pores 410 and a plurality of tissue ingrowth passages 420defined therein. The passages 420 can be formed in a variety of waysfurther described herein such as punching, drilling, tooling, and/orwith water jets and/or lasers. The implantable layer 400 also includes asurface treatment region 422 on at least one face of the body 402. Forexample, a tissue-contacting face 404 a of the body 402 includes thesurface treatment region 422.

The surface treatment used to create the surface treatment region 422 isconfigured to roughen, abrade and/or grind the tissue-contacting face404 a of the implantable layer 400, for example. In instances where aclosed cell or closed pore is adjacent to and out of contact with thetissue-contacting face 404 a, the surface treatment can open the closedcell to the tissue-contacting face 404 a, for example. The surfacetreatment region 422 is configured to provide inlets into the innerportion of the body 402. In instances where the outer portion or shellof the body 402 is denser, and/or less porous, than the inner portion,such as when the body 402 comprises a lyophilized foam body, forexample, the surface treatment region 422 may provide inlets through theouter portion toward the inner portion. For example, the outer portionof the body 402 may comprise a closed or substantially closed cellularstructure, and the surface treatment can open at least one closed poreand/or cell positioned adjacent to and/or near the tissue-contactingface 404 a to provide an inlet into the inner portion of the body 402.

In various instances, the surface treatment can include needle tuftingand/or felting of the tissue-contacting face 404 a of the body 402.Additionally or alternatively, the surface treatment can include sandand/or grit blasting, gas blasting such as dry-ice or CO₂ blasting,and/or machining such as grinding, mill cutting, and/or fly cutting, forexample. In certain instances, a fibrous outer coating can be applied tothe body 402. For example, the body 402 can be treated with a melt-blownnon-woven process to create fibers on at least a portion of at least oneface of the body 402, such as on the tissue-contacting face 404 a.Various alternative fibrous coatings and applications are furtherdescribed herein.

In various instances, it can be desirable to accelerate the degradation,absorption, and/or disintegration of at least a portion of the materialcomprising an implantable layer. Tissue ingrowth may increase as theimplantable layer degrades. To facilitate and/or expedite the ingrowthof tissue, in certain instances, the degradation profile of theimplantable layer can be accelerated. More specifically, the implantablelayer can be subjected to treatments and/or processes that promotedegradation of the implantable layer prior to implantation of the layer.In various instances, the implantable layer can be degraded beforeand/or after the implantable layer has been attached to a staplecartridge. For example, an implantable layer comprising a piece of foam,such as a piece of lyophilized foam, can be attached to a staplecartridge and purposefully degraded to a certain degree before thestapling operation. The degradation process can be terminated and/orsubstantially stalled when the desired degree of degradation has beenachieved. Natural degradation of the implantable layer may resume whenthe layer is implanted in the patient's tissue, for example.

In at least one instance, an implantable layer can be degraded withradiation therapy. For example, in an irradiation treatment, theimplantable layer can be degraded up to 45 kGy. In other instances, theimplantable layer can be degraded below 45 kGy or above 45 kGy.Radiation may be applied to the implantable layer after the layer hasbeen attached to a staple cartridge. For example, a piece of lyophilizedfoam can be manufactured and/or otherwise obtained and attached to thestaple cartridge. In certain instances, the piece of foam can be cut toa predefined shape and/or otherwise processed. The piece of foam canthen be subjected to radiation therapy. The radiation can be in the formof gamma waves and/or E-beam waves, for example.

After the piece of foam (i.e. the implantable layer) has beenirradiated, the staple cartridge including the implantable layerattached thereto can be sterilized and/or packaged. For example, thestaple cartridge can undergo an ethylene oxide (EtO) sterilizationprocess. The EtO sterilization process can include vacuum drying and/orhot room treatments. Such processes can terminate and/or stalldegradation of the implantable layer that was initiated by theirradiation treatment. For example, the free radical by-products fromthe radiation can be eliminated during EtO sterilization and prior topackaging of the staple cartridge.

Referring again to FIG. 5, a surface treatment can include etching atleast a portion of the body 402 of the implantable layer 400. Etchingcan expedite degradation of at least portions of the implantable layer400, alter the surface energy of the implantable layer, and/or createinlets and/or tissue ingrowth passages from an outer portion of theimplantable layer toward an inner portion. In a solvent etching process,a solvent is applied to the body 402, and the portions of the body 402in contact with the solvent become etched and/or degraded. For example,the solvent can be configured to degrade the contacted polymer chains inthe body 402. In various instances, a nebulized solvent can be appliedto the implantable layer 400. In other instances, a solvent-soaked padcan be positioned adjacent to the implantable layer 400 and/or containedwithin a package comprising the implantable layer 400. The solvent cansoak into or other otherwise spread throughout the internal structure ofthe body 402. The solvent can comprise potassium hydroxide (KOH),1,4-Dioxane, methyl ethyl ketone, methyl propyl ketone, acetone,toluene, and/or DIESTONE HFP manufactured by Socomore of Vannes, France,for example.

In certain instances, the pressure can be varied to facilitatedispersion of the solvent throughout the implantable layer. For example,the implantable layer 400 having a solvent applied thereto can besubjected to positive and/or negative pressures. In various instances,the temperature and exposure time can be controlled to ensure that thesolvent is dispersed through the layer 400. The solvent etching processcan occur during a processing step and/or during sterilization. Forexample, the solvent can be applied to the layer 400, along with theappropriate pressure, during an ethylene oxide (EtO) sterilizationprocess.

The solvent is configured to etch the surface(s) of the implantablelayer 400. For example, the solvent can etch the surface(s) contacted bythe solvent and subjected to the appropriate etching conditions (e.g.time, temperature, pressure). The etching process is configured toroughen and/or crack portions of the body 402. For example, the outerportion of the body 402 can be etched, which can provide inlets and/ortissue ingrowth passages into the inner portion of the body 402. Theetched surface(s) and/or portions of the body 402 can promote celladhesion to the body 402 and the degradation of the body 402, which maypromote tissue ingrowth.

In various instances, it can be desirable to alter the surface energy ofan implantable layer. For example, in certain instances, the untreatedsurface of the implantable layer body can include a substantially smoothand/or flat portion and/or scalloped pore surfaces. Such surfaces maydiscourage cell adhesion. For example, the surface of a piece oflyophilized foam can be substantially smooth and flat, and the outerportion of the foam can be denser than the inner portion of the foam.Moreover, the surface of a piece of lyophilized foam can be hydrophobic,which can further hinder the adherence of cells thereto. Increased celladherence and/or cell motility can improve tissue ingrowth. Morespecifically, when cells can adhere and move along the surface and/orinto the body of the implantable layer, the ingrowth of tissue may bemore likely to occur and/or more involved. As further described herein,in various instances, the surface energy of an implantable layer can bealtered by the addition of a coating to the body of the layer and/or byapplying energy to the body to modify the surface energy thereof.

For example, an implantable layer can be exposed to plasma to modify thesurface energy of the layer and create surface functionalities thatpromote tissue ingrowth. For example, exposure to plasma can createsurface functionalities on the body of the layer, which may promote celladhesion and/or cell motility. Functionalities may include carboxylgroups and/or hydroxyl groups, for example. In such instances, a plasmatreatment can modify the surface energy of the foam to promote celladhesion and/or motility, which can promote the ingrowth of tissue.

In various instances, the layer 400 can be treated with a corona or airplasma treatment in which the layer 400 is passed through lowtemperature plasma to change the surface energy of the layer 400. Thelayer 400 can be exposed to the plasma for a predefined period of time.For example, the layer 400 can be exposed to the plasma for less than 10minutes. In other instances, the exposure period can be more than 10minutes or less than 5 minutes. The plasma can be generated at a lowpower level to prevent melting of the body 402. Such a plasma treatmentcan be configured to modify the surface energy of the layer 400 topromote cell adhesion and/or cell motility, which can improve theingrowth of tissue, for example.

Additionally or alternatively, the surface energy of the layer 400 canbe altered with the addition of a coating thereto. For example, a pieceof lyophilized foam can be coated with a hydrophilic material, such as ahydrophilic polymer, for example, to attract water and thus increasecell adhesion. In various instances, the coating can be permanentlygrafted to the body 402 of the layer 400. The hydrophilic coating cancomprise a biocompatible hydrophilic coating such as SLIPSKIN™ 90/10 byINterface BIOmaterials BV, butyl methacrylate (BMA), and/or HYDROLAST™by AST Products, Inc., for example. Such a hydrophilic surface coatingcan be configured to modify the surface energy of the layer 400 toimprove cell adhesion and/or cell motility, which can promote theingrowth of tissue.

In certain instances, an implantable layer can include a fibrous outerlayer. The fibrous outer layer can provide an anchor or foothold fortissue ingrowth. For example, in instances where the body of theimplantable layer, or at least an outer portion of the body, isinhospitable to tissue ingrowth (e.g. dense and/or lacking a sufficientopen cell structure), tissue ingrowth can initiate in the fibrous outerlayer, gain traction, and propagate into the body of the implantablelayer.

Referring primarily to FIGS. 6-8, an implantable layer 500 including abody 502 and a fibrous layer 508 is depicted. The implantable layer 500comprises a tissue thickness compensator. For example, referring to FIG.8, when the implantable layer 500 and tissue T are captured within astaple 560, the implantable layer 500 is configured to compensate forvariations in tissue properties, such as variations in the thickness oftissue T, for example. The implantable layer 500 includes a plurality ofpores 510 (FIGS. 7 and 8) and a plurality of tissue ingrowth passages520 (FIGS. 7 and 8) defined in the body 502 thereof. For example, thebody 502 can comprise a piece of lyophilized foam having a plurality ofpores 510. The passages 520 can be formed via one or more processesfurther described herein utilizing punching, drilling, tooling, waterjets and/or lasers, for example. The body 502 includes a plurality offaces 504 including a tissue-facing face 504 a.

The fibrous layer 508 is positioned adjacent to the tissue-facing face504 a of the body 502. In certain instances, the fibrous layer 508 canextend around multiple faces 504 of the body 502. Additionally oralternatively, the implantable layer 500 can include a plurality offibrous layers 508, which can be positioned on different faces 504 ofthe body 502 and/or can cover different portions of at least one face504 of the body 502. For example, strips and/or pieces of a fibrousmaterial can be attached to the body 502 of the implantable layer 500.In various instances, the fibrous layer 508 is comprised of non-wovenfibers 509. For example, the fibrous layer 508 is comprised ofmelt-blown non-woven fibers 509. In other instances, the fibrous layer508 can be comprised of woven fibers.

The body 502 of the implantable layer 500 is denser than the fibrouslayer 508. For example, the body 502 comprises a first density and thefibrous layer 508 comprises a second density that is less than the firstdensity. More specifically, the lyophilized foam that forms the body 502is denser than the melt-blown non-woven fibers that form the fibrouslayer 508. Referring primarily to FIG. 8, the fibrous layer 508 isconfigured to contact tissue T during a stapling operating. The tissue Tis configured to initially grow into the more hospitable, less densefibrous layer 508 before reaching the less hospitable, denser body 502of the implantable layer 500. For example, in the exemplary staplingoperation depicted in FIG. 8, portions of the tissue T₁ and T₂ havegrown through the fibrous layer 508 and into the tissue ingrowthchannels 520 a and 520 b, respectively, in the body 502. In otherinstances, the body 502 may not include tissue ingrowth channels 520,however, in such instances, the fibrous layer 508 can be configured toprovide sufficient footholds and/or traction to facilitate tissueingrowth into the implantable layer 500.

Referring now to FIG. 9, an implantable layer 600 comprising a body 602and a fibrous layer 608 is depicted. The implantable layer 600 comprisesa tissue thickness compensator. In various instances, the implantablelayer 600 can be similar in many aspects to the implantable layer 500.For example, the body 602 can comprise a piece of lyophilized foam.Additionally or alternatively, the body 602 can include a plurality ofpores and/or a plurality of tissue ingrowth passages defined therein.The body 602 of the implantable layer 600 is denser than the fibrouslayer 608.

The fibrous layer 608 comprises a layer or sheet of fibrous material.For example, the fibrous layer 608 comprises a woven mesh. The meshcomprises a lattice or netting of fibers 609 that are interwoven andinterlaced. The fibrous layer 608 overlies a tissue-facing face of thebody 602. In the depicted embodiment, the fibrous layer 608 covers thetissue-facing face of the body 602. In other embodiments, the fibrouslayer 608 may cover a portion or portions of the tissue-facing faceand/or may extend around additional faces of the body 602. The fibrouslayer 608 is secured to the body 602 at a plurality of engagementregions 618. For example, the fibrous layer 608 is heat-staked to thebody 602 at each engagement region 618. Additionally or alternatively,the fibrous layer 608 can be solvent-bonded to the body 602, securedwith at least one suture, and/or otherwise affixed to at least a portionof the body 602. In certain instances, the implantable layer 600 caninclude a plurality of fibrous layers 608, which can be affixed to thebody 602 of the implantable layer 600 and/or to each other.

Referring now to FIG. 10, a fibrous layer 708 is depicted. The fibrouslayer 708 can be used with various implantable layers and/or bodiesthereof that are further described herein. The fibrous layer 708comprises a plurality of fibers 709 that are woven into a mesh orlattice pocket 716. The lattice pocket 716 is configured to bepositioned around the body of an implantable layer. In variousinstances, the lattice pocket 716 can be positioned around and/orotherwise attached to an implantable layer before the implantable layeris attached to a staple cartridge and/or end effector.

In various instances, multiple lattice pockets 716 can be positionedaround at least a portion of the body of an implantable layer. Forexample, multiple lattice pockets 716 can be layered around at least aportion of the body of an implantable layer. Additionally oralternatively, in instances where the implantable layer comprises aplurality of body portions, at least one lattice pocket 716 can bepositioned around different body portions of the implantable layer. Forexample, individually-wrapped or individually-covered body portions ofan implantable layer can be positioned on either side of a longitudinalknife slot and/or firing path in a staple cartridge.

In various instances, an implantable layer can be comprised of multiplepieces of porous material, such as multiple foam fragments. As describedin greater detail herein, the multiple pieces of porous material can befused together under conditions of increased temperature and/or pressureto form the implantable layer. In certain instances, pores can bedefined in the foam fragments that form the implantable layer and gapscan exist between adjacent foam fragments in the formed implantablelayer. In such instances, the implantable layer includes intrastitialvoids (e.g. the pores in the foam fragments) and interstitial voids(e.g. the gaps between the foam fragments). The intrastitial voids canbe smaller than the interstitial voids, for example, and the variationin void size in the implantable layer may facilitate tissue ingrowth.For example, the tissue can initially grow into the larger voids betweenadjacent pieces of porous material before permeating the smaller voidswithin a piece of porous material. As further described herein, theproperties of the foam fragments (e.g. size, material, density, etc.)can be selected to adjust the properties of the implantable layer. Anexemplary implantable layer 800 comprising a conglomeration of foamfragments is depicted in FIG. 11. The implantable layer 800 includes aplurality of foam fragments that have been fused together to form animplantable body 802. Interstitial voids 806 are defined betweenadjacent foam pieces in the body 802.

Referring primarily to FIG. 12, a portion of a staple cartridge 950 isshown. The staple cartridge 950 includes a cartridge body 952 having adeck 956. A plurality of staple cavities are defined in the cartridgebody 952, and each staple cavity comprises an opening in the deck 956.For example, a staple cavity 954 is defined in the cartridge body 952.The staple cartridge 950 further includes a plurality of staples. Forexample, a staple 960 is positioned in the staple cavity 954. The staplecartridge 950 includes an implantable layer 900, which is positionedadjacent to the deck 956 of the cartridge body 952. The implantablelayer 900 extends over the openings in the deck 956. The implantablelayer 900 can be releasably attached to the cartridge body 952. Theimplantable layer 900 comprises a tissue thickness compensator. Forexample, referring now to FIG. 13, when the implantable layer 900 andtissue T are captured within the staple 960, the implantable layer 900is configured to compensate for variations in tissue properties, such asvariations in the thickness of tissue T, for example.

The implantable layer 900 includes a plurality of foam fragments 908. Asfurther described herein, the foam fragments 908 are fused togetherunder conditions of increased temperature and/or pressure to form a body902 of the implantable layer 900. The body 902 includes a plurality ofinterstitial voids 906. For example, interstitial voids 906 are definedbetween adjacent foam fragments 908 in the body 902. Referring primarilyto FIG. 12, the foam fragments 908 are angularly-oriented throughout thebody 902. For example, a first foam fragment 908 a is angularly-orientedrelative to a second foam fragment 908 b. In the depicted instance, theangular orientation of the foam fragments 908 is random. In otherinstances, the foam fragments 908 can be systematically oriented and/orpurposefully arranged throughout the body 902.

A portion of an implantable layer 1000 is depicted in FIG. 14. Similarto the implantable layers 800 and 900, the implantable layer 1000includes a plurality of foam fragments 1008. As further describedherein, the foam fragments 1008 are fused together under conditions ofincreased temperature and/or pressure to form a body 1002 of theimplantable layer 1000. The body 1002 also includes a plurality ofinterstitial voids 1006. For example, interstitial voids 1006 aredefined between adjacent foam fragments 1008 in the body 1002. The foamfragments 1008 include a plurality of pores 1010 defined therein. Thepores 1010 comprise intrastitial voids of the body 1002. Theinterstitial voids 1006 are larger than the intrastitial voids 1010 inthe body 1002.

The interstitial voids 1006 can vary in size depending on theorientation and size of the foam fragments 1008, among other factors. Ininstances where the foam fragments 1008 are randomly-oriented in thebody 1002, the interstitial voids 1006 can be randomly-sized, forexample. The interstitial voids 1006 can vary in size betweenpore-sized, compressed pore-sized, open-cell sized, and/or orders ofmagnitude greater than the size of the pores 1010. In the depictedembodiment, the interstitial voids 1006 are approximately ten times toone hundred times larger than the intrastitial voids 1010, for example.In other instances, at least one interstitial void 1006 can be less thanten times larger than at least one intrastitial void 1010 and/or atleast one interstitial void 1006 can be greater than one hundred timeslarger than at least one intrastitial void 1010, for example.

Referring still to FIG. 14, the size of the pores 1010 can vary betweenand among the foam fragments 1008. For example, different types of foamcan have different size pores. Additionally, at least a portion of thepores 1010 can become compressed and shrink during the process of fusingthe foam fragments 1008 together to form the body 1002. In variousinstances, more compressed foam fragments 1008 and/or portions thereofcan comprise an increased density compared to less compressed foamfragments 1008 and/or portions thereof having the same materialproperties. The size of at least one interstitial void 1006 can alsodepend on the compression applied to the foam fragments 1008 during thefusing process.

In certain instances, foam fragments for an implantable layer can berandomly selected and combined to form an implantable layer. In otherinstances, the foam fragments can be sorted by size, shape, material,age, etc., and foam fragments having specific material properties can berecombined to form the implantable layer. In such instances, theproperties of the resultant implantable layer can be adjusted based onthe selected material properties of the foam fragments. For example,referring to FIG. 16, a portion of an implantable layer 1200 isdepicted. The implantable layer 1200 includes foam fragments 1208comprising different material properties. The foam fragments 1208 can beselected based on the material properties thereof to control variousproperties of the resultant implantable layer 1200. In certaininstances, as further described herein, the foam fragments within animplantable layer can be organized or selectively arranged such that theimplantable layer comprises different properties in different regionsthereof.

The type of foam fragments can be selected based on the desiredproperties for the implantable layer. For example, the size(s) of thefoam fragments can affect the properties of the implantable layer formedtherefrom. In certain instances, the porosity of an implantable layercan be greater when larger foam fragments are used and the porosity ofan implantable layer can be less when smaller foam fragments are used.For example, due to a decrease in packing efficiency, largerinterstitial voids can exist between larger foam fragments than betweensmaller foam fragments. The densities of the foam fragments can alsoaffect the properties of the implantable layer formed therefrom. Incertain instances, the porosity of an implantable layer can be less whendenser foam fragments are used and the porosity of an implantable layercan be greater when less dense foam fragments are used.

The size of the foam fragments can vary from approximately 1.5 mm toapproximately 0.1 mm, for example. Referring to FIG. 15A, large foamfragments 1108 can be combined to form the body 1102 of an implantablelayer. The foam fragments 1108 can be approximately 1.5 mm in at leastone dimension, for example. In other instances, referring to FIG. 15C,small foam fragments 1118 can be combined to form the body 1112 of animplantable layer. The foam fragments 1118 can be approximately 0.1 mmin at least one dimension, for example. The interstitial voids 1106formed between the large foam fragments 1108 (FIG. 15A) are larger thanthe interstitial voids 1116 formed between the small fragments 1118(FIG. 15C). As a result, the body 1102 (FIG. 15A) is more porous thanthe body 1112 (FIG. 15C). In certain instances, different sizedfragments can be combined in a single body. In such instances, smallerfoam fragments can at least partially fill the larger voids formedbetween the larger foam fragments.

Referring to FIGS. 15A and 15B, the foam fragments 1108 are denser thanthe foam fragments 1128. The intrastitial voids 1110 formed in the foamfragments 1108 (FIG. 15A) are smaller than the intrastitial voids 1130formed in the foam fragments 1128 (FIG. 15B). In other words, the foamfragments 1128 are more porous than the foam fragments 1108. As aresult, the body 1102 (FIG. 15A) is less porous than the body 1122 (FIG.15B). In certain instances, foam fragments having different porositiescan be combined in a single body. The porosity of a foam fragment candepend on the porosity of the foam from which the fragment was taken.Additionally, the porosity of a foam fragment can depend on the materialof the foam and the process of manufacturing the foam (e.g. the degreeof compression).

In certain instances, adjunct materials, such as at least one fiber,collagen, and/or medicament, can be combined with foam fragments to forma body of an implantable layer. The adjuncts can be selected to affectdifferent properties of the resultant implantable layer. Referring toFIG. 15D, a plurality of fibers 1134 can be combined with a plurality offoam fragments 1138 to form a body 1132 of an implantable layer. Thefibers 1134 at least partially fill the interstitial voids 1136 betweenadjacent foam fragments 1138, and are configured to promote tissueingrowth. More specifically, the addition or fibers 1134 to the body1132 can increase the porosity of the body 1132 and/or provideadditional footholds and/or inlets for tissue ingrowth. The fibers 1134can be randomly-oriented, loose fibers, such as the collection of fibers1144 depicted in FIG. 15E, and/or can comprise a woven or knitted matrixof fibers, such as the arrangement of fibers 1154 depicted in FIG. 15F.

Referring again to FIG. 16, the implantable layer 1200 is formed fromthe foam fragments 1208 that have been fused together, as furtherdescribed herein. The foam fragments 1208 forming the body 1202 of theimplantable layer 1200 comprise different material properties. Forexample, the foam fragments 1208 comprise different sizes and differentmaterials. A plurality of first foam fragments 1208 a fit within a firstrange of sizes and are formed from a first material, a plurality ofsecond foam fragments 1208 b fit within a second range of sizes and areformed from a second material, and a plurality of third foam fragments1208 c fit within a third range of sizes and are formed from a thirdmaterial. The first foam fragments 1208 a comprise a different densitythan the second foam fragments 1208 b and the third foam fragments 1208c. Moreover, the second foam fragments 1208 comprise a different densitythan the third foam fragments 1208 c. In various instances, as furtherdescribed herein, the groups of foam fragments 1208 a, 1208 b, 1208 ccan also comprise different degradation or absorption rates. Forinstance, PCL foams degrade slower than PCL/PGA foams. The PCL foamswill also be stiffer than the PCL/PGA foams. This is true even withsimilar morphologies, densities, etc.

In certain instances, the foam fragments can be systematically arrangedwithin the body of the implantable layer. For example, a first group offoam fragments or the majority thereof, such as the foam fragments 1208a, can be positioned in a first region, a second group of foam fragmentsor the majority thereof, such as the foam fragments 1208 b, can bepositioned in a second region, and a third group of foam fragments orthe majority thereof, such as the foam fragments 1208 c, can bepositioned in a third region. In such instances, the properties of theresultant implantable layer can vary between the regions. For example,the porosity, density, thickness, resiliency, compressibility, and/orflexibility of the implantable layer can vary between regions. In atleast one instance, regions can correspond to the arrangement of staplecavities in a staple cartridge. For example, the regions can compriseelongate regions that overlie or substantially overlie rows of staplecavities in the staple cartridge. In at least one instance, thethickness of the implantable body can vary across rows of staplecavities. For example, the implantable body can comprise a firstthickness in the elongate regions adjacent to a knife slot and/or afiring path through the staple cartridge and the thickness of theimplantable body can gradually and/or incrementally decrease laterallyoutboard from the knife slot and/or the firing path. In other instances,other properties of the implantable body can vary laterally outboardfrom the knife slot and/or the firing path. For example, the porosity,density, resiliency, compressibility, and/or flexibility of the body canvary, increase or decrease, laterally outboard.

In certain instances, the adjuncts that are combined with various foamfragments can demonstrate antibacterial properties. Antibacterialmedicaments in an implantable layer can be time-released, graduallyreleased, and/or incrementally released from the implantable layer.Embodiments having controlled release of an antibacterial medicament mayminimize and/or prevent the incidence and/or severity of infection atthe surgical site, for example. In various instances, medicaments in theimplantable layer can comprise additional and/or different medicinalproperties.

The release rate of medicaments from an implantable layer that iscomprised of fused foam fragments can depend on the properties of thefoam fragments, such as the size, density, material, and/or age of thefoam fragments. More specifically, certain foam fragments can degrade orabsorb faster than other foam fragments. Additionally or alternatively,the age of the material that forms the foam fragment can affect theabsorption rate. In certain instances, various foam fragments and/oradjuncts can be aged or matured prior to the formation of theimplantable layer, which can accelerate the degradation profile of thecomposite implantable layer. To facilitate the desired release ofmedicament(s), the type of foam fragment(s) can be selected based on thedegradation rate(s) thereof, and thus, the corresponding release rate(s)of any medicaments combined therewith.

Referring now to FIG. 17, a graph 1300 depicting the release ofmedicaments from an implantable layer over a period of time is depicted.In the depicted embodiment, the release of medicament A from a firstgroup of foam fragments occurs faster and is completed sooner than therelease of medicament B from a second group of foam fragments. The foamfragments in the first group comprise a degradation or absorption ratethat exceeds the degradation or absorption rate of the foam fragments inthe second group. In other instances, medicament A may be entirely orsubstantially released before medicament B is released or vice versa. Insuch instances, the release of medicament A and medicament B may notoccur simultaneously. Additionally or alternatively, the rate of releaseof medicament A and medicament B can be equal or substantially equaland/or the volume of released medicament A and volume of releasedmedicament B can be equal or substantially equal.

Additionally or alternatively, the degradation profile of an implantablelayer can be selected to facilitate tissue ingrowth. For example, asportions of the implantable layer degrade, additional and/or largertissue ingrowth passages can be formed in the implantable layer. In atleast one instance, a first group of foam fragments can be configured todegrade more quickly than a second group of foam fragments such thattissue ingrowth passages in the implantable layer are quickly formedbetween the foam fragments of the second group in the absence of thefoam fragments of the first group. In certain instances, the arrangementof foam fragments can be controlled to create predefined tissue ingrowthregions or passages in the implantable layer. For example, certainregions of the implantable layer can comprise a degradation orabsorption rate that exceeds the degradation or absorption rate of theadjacent region(s) such that specific ingrowth passages are defined inthe implantable layer after a predefined period of time.

In various instances, an implantable layer can comprise foam fragmentshaving specific geometries. Referring now to FIGS. 18-20, implantablelayers comprised of foam fragment having different geometries aredepicted. The implantable layer 1400 includes arced, or arcuate, foamfragments 1408 (FIG. 18), the implantable layer 1500 includes sphericalfoam fragments 1508 (FIG. 19), and the implantable layer 1600 includesstar-shaped foam fragments 1608. In certain instances, foam fragmentscan be ovoid, diamond-shaped, triangular, and/or other three-dimensionalshapes, for example. The geometry of the foam fragments 1408, 1508, and1608 affects how the foam fragments 1408, 1508, 1608 fit together and,thus, affects the voids or tissue ingrowth regions therebetween. Forexample, foam fragments of certain shapes can be configured to nesttogether, which results in a high packing efficiency and, thus, fewerand/or smaller tissue ingrowth voids therebetween. Alternatively, foamfragments of other shapes can be configured to maintain a low packingefficiency, which can result in more and/or larger tissue ingrowth voidstherebetween. In certain instances, foam fragments comprising differentgeometries can be combined in an implantable layer.

Implantable layers comprising a plurality of foam fragments, such as thecomposite implantable layers 800, 900, 1000, 1200, 1400, 1500, and 1600described above, for example, can be formed by fusing or otherwiseadhering multiple foam fragments together to form a unitary piece. Thefoam fragments can be fused together under conditions of increasedtemperature and/or pressure. For example, a plurality of molded foamfragments can be positioned in a cavity of a mold. The cavity can definethe desired geometry of the implantable layer. In other instances, theunitary conglomeration of foam fragments can be cut or otherwise trimmedto the desired size and/or geometry for the implantable layer after thetemperature and/or pressure has been applied. In certain instances, foamfragments can be sorted before filling the mold cavity and only foamfragments comprising certain characteristics (e.g. within a defined sizerange and/or having certain material properties) can be positioned inthe cavity of the mold. Foam fragments having different characteristicscan be combined in the mold cavity and/or adjuncts can be combined withthe foam fragments. Additionally, heat and pressure can be applied tothe foam fragments, which can fuse the foam fragments together. Anyadjunct material can also be molded into the unitary piececonglomeration between foam fragments. In certain instances, the foamfragments and/or the adjuncts, if any, can be randomly or uniformlydispersed throughout the mold cavity prior to the application of heatand/or pressure thereto. In other instances, the foam fragments and/orthe adjuncts, if any, can be systematically arranged and/or organized inthe mold cavity prior to the application of heat and/or pressurethereto.

Referring primarily to FIGS. 21 and 22, a portion of a mold 1730 forforming a composite implantable layer is depicted. The mold 1730comprises sidewalls 1731 defining a cavity 1732 for receiving aplurality of foam fragments 1708. The cavity 1732 can comprise ageometry that corresponds to the desired geometry of a compositeimplantable layer. In other instances, a piece and/or sheet of compositeimplantable material can be formed in the mold cavity 1732, and themolded piece and/or sheet can be cut and/or otherwise trimmed to thedesired size and/or shape for an implantable layer.

The foam fragments 1708 are randomly distributed and randomly orientedthroughout the mold cavity 1732. Referring primarily to FIG. 23, a groupof uncompressed and unfused foam fragments 1708 from the mold cavity1732 are depicted. The foam fragments 1708 fill a first volume of spacebefore the application of pressure thereto. In the depicted embodimentof FIG. 21, a portion of the foam fragments 1708 are positioned above arim or top edge 1734 of the mold cavity 1732. In such instances, thefirst volume of space consumed by the foam fragments 1708 comprises alarger volume than the volume of the mold cavity 1732. In otherinstances, the mold cavity 1732 may not be entirely filled with foamfragments 1708 or the foam fragments 1708 may fill the mold cavity 1732to the top edge 1734.

Referring primarily to FIG. 22, a press 1736 is configured to applypressure to the foam fragments 1708 positioned in the mold cavity 1732.The press 1736 comprises a geometric shape that mates with the geometryof the mold cavity 1732 to form a flat or substantially flat compositeimplantable layer. For example, the press 1736 fits within the moldcavity 1732 with minimal clearance between the press 1736 and thesidewalls 1731 of the mold 1730. While the press 1736 is compressing thefoam fragments 1708 positioned in the mold cavity 1732, the mold 1730and/or the foam fragments 1708 therein are heated to an elevatedtemperature. For example, the mold 1730 is configured to be heated to atemperature above the ambient temperature before and/or while the foamfragments 1708 are being compressed by the press 1736. As thetemperature of the mold 1730 increases, the heat is transferred to thefoam fragments 1708 in the mold cavity 1732. As a result, the foamfragments 1708 are also heated above the ambient temperature.Specifically, the foam fragments 1708 can be heated to a temperatureabove the glass transition temperature and below the melting temperaturethereof. In other instances, heat can be applied directly to the foamfragments 1708 positioned in the mold cavity 1732.

When the foam fragments 1708 are heated between their glass transitiontemperature and their melting temperature and/or concurrently subjectedto pressure between the mold 1730 and the press 1736, the foam fragments1708 become fused together. Referring primarily now to FIG. 24, thegroup of foam fragments 1708 shown in FIG. 23 are compressed and fusedtogether with the application of heat and pressure. The foam fragments1708 are compressed and the spaces between adjacent foam fragments 1708are also compressed during the compression treatment by the press 1736(FIG. 22). In other words, the interstitial voids and the intrastitialvoids that existed prior to the forming process have been compressed,but not completely eliminated.

After the foam fragments 1708 have fused together, the foam fragments1708 can be actively cooled and/or allowed to cool at ambienttemperature. After the foam fragments 1708 have melded together andsufficiently cooled to form a consolidated amalgamation of foamfragments, the composite foam assembly can be removed from the moldcavity 1732 and applied or assembled to a staple cartridge. In certaininstances, the composite foam assembly can undergo additional processingsteps (e.g. cutting, reshaping, drilling, and/or various surfacetreatments) before being applied to a staple cartridge.

Referring primarily now to FIGS. 25-27, foam fragments for formingcomposite implantable layers, such as the various foam fragmentsdescribed above, for example, can be ground from a piece of foam. Forexample, a homogenous or substantially homogenous piece of foam 1840 isfed through a grinder mechanism 1842 (FIG. 25), which grinds and/or cutsthe foam 1840 into a plurality of fragments 1808. The fragments 1808 arethen fed through a plurality of sieves or filters 1844 a, 1844 b, 1844 c(FIG. 25), which sort the fragments 1808 by size. The filters 1844 a,1844 b, 1844 c also comprise conveyors for moving the sorted fragments1808 a, 1808 b, 1808 c. The largest fragments 1808 a are captured by thefirst filter 1844 a, while the smaller fragments 1808 b and 1808 c passthrough the first filter 1844 a. The second filter 1844 b is configuredto capture the mid-sized fragments 1808 b, while the smaller fragments1808 c pass through the second filter 1844 b. The third filter 1844 c isconfigured to capture the smaller fragments 1808 c.

In certain instances, fragments below a certain size and/or above acertain size may be undesirable. Referring now to FIGS. 26 and 27, foamfragments for forming composite implantable layers can preferably rangein size from 1.5 mm to 0.1 mm, and foam fragments greater than 1.5 mmand less than 0.1 mm may not be combined to form a composite layer, forexample. In other instances, at least one foam fragment can be greaterthan 1.5 mm in at least one dimension and/or less than 0.1 mm in atleast one dimension.

The foam fragments can be sorted by size, as described above.Additionally or alternatively, foam fragments can be sorted by at leastone material property thereof. In certain instances, an implantablelayer can be formed from foam segments comprising similar sizes and/ormaterial properties. In other instances, foam fragments comprisingdifferent sizes and/or material properties can be combined to tuneand/or optimize various characteristics of the resultant implantablelayer.

Various implantable layers described herein and/or at least a portion ofthe various implantable layers described herein can comprise a piece oflyophilized foam. For example, the implantable body portion of animplantable layer can comprise a piece of lyophilized foam. Lyophilizedfoam comprises an inherently porous structure, however, the poresdefined in lyophilized foam can be small. For example, the pores definedin a piece of conventionally-molded lyophilized foam can be betweenapproximately 5 μm and approximately 50 μm in diameter, for example.Larger pores may be more conducive to tissue ingrowth. For example,pores between approximately 100 μm and approximately 150 μm in diametermay promote and/or encourage tissue ingrowth. Moreover, pores largerthan 125 μm in diameter, for example, may promote and/or encouragetissue ingrowth. That said, such pores may be spherical, but theyfrequently comprise an irregular shape. Additionally, a piece ofconventionally-molded lyophilized foam can comprise an outer portion orshell that is denser and/or less porous than the inner portion. Topromote tissue ingrowth, it may be desirable to increase the porosityand/or the pore size and/or to create additional tissue ingrowth inletsand/or passages into and/or through the lyophilized foam.

In at least one instance, gas bubbles can be introduced into alyophilization solution for forming an implantable layer. Thelyophilization solution can comprise polyglycolic acid (PGA) and/orpolycaprolactone (PCL), for example. Gas bubbles can be introduced intothe lyophilization solution by whipping and/or blowing gas into thesolution prior to freezing of the solution. For instance, nitrogen gascan be whipped and/or blown into the lyophilization solution, forexample. Moreover, the gas bubbles can be introduced before and/orduring the cooling process which gels the solution. By whipping gasbubbles into the solution as it is gelling, the bubbles are dispersedwithin the frozen solution. When a vacuum is pulled on the environmentsurrounding the frozen solution, the solvent sublimates from the solid,i.e., lyophilizes, and the gas trapped within the bubbles escapesleaving behind cavities or pores. The size of the bubbles and, thus, thesize of the pores, can be controlled by selecting the gas, the method inwhich the gas is introduced into the solution, and the whipping processparameters, for example. Due to the inherently porous structure oflyophilized foam, the foam also comprises smaller pores found inconventionally-molded lyophilized foam. As a result, the lyophilizedfoam can comprise a bimodal distribution of cells around thenaturally-occurring smaller pores (the first mode) and theintentionally-created larger bubble cells (the second mode).

The addition of larger cells into the lyophilized foam is configured topromote tissue ingrowth. In various instances, the size of the largercells can be controlled by adjusting the speed, duration, and/or toolsused to form the bubbles (e.g. whipping and/or blowing). Additionally oralternatively, the position of the larger cells can be controlled byadjusting the viscosity of the lyophilization solution and/or the timebetween the bubble formation step and the freezing step. Additionally oralternatively, in at least one instance, additional energy can beapplied to the lyophilization solution, such as by vibrating thelyophilization mold, for example, to control the position of the largercells.

Referring now to FIGS. 28 and 29, a mold 2030 for forming a piece oflyophilized foam is depicted. The mold 2030 comprises sidewalls 2031defining a cavity 2032 for receiving a lyophilization solution 2040. Thecavity 2032 can comprise a geometry that corresponds to the desiredgeometry of an implantable layer and/or a body portion thereof. Incertain instances, a piece and/or sheet of implantable material can beformed in the mold cavity 2032, and the molded piece and/or sheet can becut and/or otherwise trimmed to the desired size and/or shape.

The lyophilization solution 2040 comprises a plurality of pores 2010 anda plurality of bubbles 2018 therein. The bubbles 2018 are formed by theintroduction of gas into the solution. For example, the gas is blownand/or whipped into the lyophilization solution 2040. Referring to theembodiment depicted in FIG. 28, the gas was introduced into thelyophilization solution 2040 before the solution 2040 was provided tothe mold 2030. In other instances, the gas can be introduced into thelyophilization solution 2040 when the solution 2040 is in the mold 2030.

The arrangement of pores 2010 and bubbles 2018 in the lyophilizationsolution 2040 depicted in FIG. 28 corresponds to an initial stage in thelyophilization process, and the arrangement of pores 2019 and bubbles2018 in the lyophilization solution 2040 depicted in FIG. 29 correspondsto a secondary stage in the lyophilization process. More specifically,the bubbles 2018 are configured to move between the initial stage andthe secondary stage. For example, the bubbles 2018 are configured torise or migrate toward a top surface 2042 of the solution 2040 in themold cavity 2032. As further described herein, the pace of the movementof the bubbles 2018 toward the surface 2042 of the solution 2040 can becontrolled and/or adjusted. The pace can be adjusted by adjusting thetemperature of the solution at the time of introducing the bubbles, therate in which the solution is cooled/frozen, the rate in which thevacuum is applied, and/or the amount of vacuum, for example. As thebubbles 2018 move toward the surface 2042 of the solution 2040, tissueingrowth passages 2020 are formed in the lyophilization solution 2040.When the lyophilized solution 2040 is frozen during the lyophilizationprocess, various bubbles 2018 and the tissue ingrowth passages 2020become frozen in the solution 2040, which results in bubbles 2018 andtissue ingrowth passages 2020 in the resultant lyophilized foam.

The size of the bubbles 2018 is affected by the speed, duration, and/ortools used to form the bubbles. For example, when the lyophilizationsolution 2040 is whipped at a higher speed and/or for a longer period oftime, larger bubbles 2018 can form in the solution 2040. Additionally,the shape of the whip can affect the size of the bubbles 2018. The paceof bubble migration is affected by the viscosity of the lyophilizationsolution 2040 and the time interval between the bubble formation stepand the freezing step. For example, bubbles 2018 can migrate more slowlywhen the lyophilization solution 2040 is more viscous, and the bubbles2018 can migrate faster when the lyophilization solution 2040 is lessviscous. Additionally, as the time interval between the bubble formationstep and the freezing step lengthens, additional bubbles 2018 canmigrate toward the surface 2042, which can form additional and/or longertissue ingrowth channels 2020 in the lyophilization solution 2040.Additional energy can be applied to the lyophilization solution 2040 toincrease the rate of bubble migration. For example, the mold 2040 can bevibrated to accelerate the rise of bubbles 2018 toward the surface 2042and, thus, to form additional and/or longer tissue ingrowth channels2020 in the solution 2040 and the resultant lyophilized foam.

In certain instances, an implantable layer can comprise at least onedissolvable insert and/or particulate. Dissolvable inserts can beconfigured to dissolve prior to implantation and/or after implantationof the implantable layer (i.e. in vivo). After the dissolvable insertshave dissolved, voids remain in the implantable layer in the spacepreviously occupied by the dissolvable inserts. Voids remaining in theabsence of dissolvable inserts can form tissue ingrowth channels and/orinlets that are configured to promote the ingrowth of tissue around,into and/or through the implantable layer. In instances where thedissolvable inserts are dissolved prior to the implantation of theimplantable layer, the tissue ingrowth channels can facilitate tissueingrowth upon implantation of the implantable layer. In other instances,the tissue ingrowth channels can propagate through the implantable layerafter implantation of the layer, and the tissue ingrowth channels can beprogressively and/or increasingly available for tissue ingrowth afterimplantation of the implantable layer.

Dissolvable insert(s) can comprise less than 50% of the overall volumeof the implantable layer. In such instances, tissue ingrowth channel(s)formed in the place of the dissolvable insert(s) can occupy less than50% of the overall volume of the implantable layer. A porous structure,such as lyophilized foam, for example, can occupy the remaining volumeof the implantable layer. In other instances, the dissolvable insert cancomprise approximately 50% or more than 50% of the overall volume of theimplantable layer.

Dissolvable inserts can be bonded to the material that forms the body ofthe implantable layer. For example, dissolvable inserts can beincorporated into the implantable layer with solvent casting,particulate molding, and/or a secondary lyophilization process.Dissolvable inserts can comprise sugar crystals and/or salt crystalsthat are mixed with a lyophilization solution prior to freezing, orlyophilizing, of the solution. The sugar crystals and/or salt crystalscan be liquefied during a secondary dissolving step, for example. Afterlyophilization, in at least one such instance, there will be a porousfoam structure with dissolvable materials trapped within it. Thedissolvable materials can be solubilized with a solvent that does notaffect the base foam material. For instance, water doesn't rapidlydissolve PCL/PGA materials and, as a result, water could be used todissolve salt and/or sugar inserts that were trapped within a PCL/PGAfoam with several rinsing steps. The foam could then be dried to stopthe degradation of the PCL/PGA. In certain instances, dissolvableinserts can be layered within the body of an implantable layer.

A dissolvable insert can comprise a three-dimensional shape. Forexample, the dissolvable insert can be formed in a mold. The moldedinsert can be comprised of sugar, salt, honey, and/or VICRYL RAPIDE, forexample. VICRYL RAPIDE is a bioabsorbable material sold by Ethicon, Inc.that degrades quicker than ordinary VICRYL because it is soldpre-degraded, either by exposure to a moist environment and/or by gammaradiation exposure, for example. In certain instances, at least onedissolvable insert can be mixed into the material forming the body ofthe implantable layer and the implantable layer can be insert-moldedaround the at least one dissolvable insert. Alternatively, alyophilization solution can be provided around at least one dissolvableinsert and the implantable layer can be lyophilized around the at leastone dissolvable insert.

Referring primarily to FIG. 30, a portion of a mold 2230 for forming apiece of lyophilized foam is depicted. The mold 2230 comprises sidewalls2231 defining a cavity 2232 for receiving a lyophilization solution. Thecavity 2232 can comprise a geometry that corresponds to the desiredgeometry of an implantable layer and/or a body portion thereof. Incertain instances, a piece and/or sheet of implantable material can beformed in the mold cavity 2232, and the molded piece and/or sheet can becut and/or otherwise trimmed to the desired size and/or shape for thebody of an implantable layer.

A dissolvable insert 2270 is positioned in the mold cavity 2232. Thedissolvable insert 2270 is formed from a syrup of sugar and water;however, any suitable material may be utilized. The syrup is reduceduntil the desired concentration is obtained. The syrup is then kneadedand forced into a supplemental mold in which the syrup is cooled to formthe solidified dissolvable insert 2270. The dissolvable insert 2270includes a plurality of vertical spokes 2272 and a plurality ofhorizontal spokes 2274. The vertical spokes 2272 are parallel orsubstantially parallel. The horizontal spokes 2272 form an interlockingweb of spokes extending along the bottom portion of the insert 2270 andanother interlocking web of spokes extending along the top portion ofthe insert 2270. The vertical spokes 2272 connect the horizontal spokes2274 along the bottom portion of the insert 2270 with the horizontalspokes 2274 along the top portion of the insert 2270.

A lyophilization solution is provided around the dissolvable insert 2270in the mold cavity 2232 to form the lyophilized foam. Upon completion ofthe lyophilization process, the dissolvable insert 2270 is dissolved outof the resultant piece of lyophilized foam. In at least one instance,water, for example, can be utilized to dissolve the insert 2270. A pieceof lyophilized foam formed in the mold 2230 and with the dissolvableinsert 2270 is depicted in FIG. 31. The lyophilized foam forms animplantable layer 2200 comprising a porous body portion 2202 having aplurality of pores 2210 defined therein.

The implantable layer 2200 also includes a plurality of tissue ingrowthpassages 2220 defined therein. The tissue ingrowth passages 2220 aredefined by the voids remaining behind after the insert 2270 (FIG. 30)has been dissolved. As a result, the tissue ingrowth passages 2220comprise, one, a plurality of vertical channels which correspond to thevertical spokes 2272 and, two, webs of horizontal channels whichcorrespond to the horizontal spokes 2274. The horizontal channelsintersect the vertical channels along a face 2204 a of the implantablelayer 2200; however, the vertical channels can intersect in any suitablemanner. In use, the face 2204 a comprises a tissue-facing face and thetissue ingrowth passages 2220 propagating therefrom are configured topromote the ingrowth of tissue from the tissue-facing face 2204 aaround, into and/or through the implantable layer 2200.

Referring primarily to FIG. 30, a portion of a mold 2330 for forming apiece of lyophilized foam is depicted. The mold 2330 comprises sidewalls2331 defining a cavity 2332 for receiving a lyophilization solution. Thecavity 2332 can comprise a geometry that corresponds to the desiredgeometry of an implantable layer and/or a body portion thereof. Incertain instances, a piece and/or sheet of implantable material can beformed in the mold cavity 2332, and the molded piece and/or sheet can becut and/or otherwise trimmed to the desired size and/or shape for thebody of an implantable layer.

A dissolvable insert 2370 is positioned in the mold cavity 2332. Thedissolvable insert 2370 is formed from a syrup of sugar and water;however, any suitable material could be utilized. The syrup is reduceduntil the desired concentration is obtained. The syrup is then kneadedand forced into a supplemental mold in which the syrup is cooled to formthe solidified dissolvable insert 2370. The dissolvable insert 2370includes a plurality of vertical spokes 2372 and a plurality ofhorizontal spokes 2374. The vertical spokes 2372 are parallel orsubstantially parallel. Various vertical spokes 2372 comprise a variablediameter that tapers intermediate a top portion of the dissolvableinsert 2370 and a bottom portion of the dissolvable insert 2370. Thehorizontal spokes 2372 form an interlocking matrix of spokes extendingalong the bottom portion of the insert 2370 and another interlockingmatrix of spokes extending along the top portion of the insert 2370. Thevertical spokes 2372 connect the horizontal spokes 2374 along the bottomportion of the insert 2370 with the horizontal spokes 2374 along the topportion of the insert 2370. The shape and/or various dimensions of thespokes 2372, 2374 can vary along the length and/or width of thedissolvable insert 2370. For example, thicker vertical spokes 2372 arepositioned along a central portion of the dissolvable insert 2370. Invarious instances, the thicker vertical spokes 2372 at a central regionin the dissolvable insert 2370 are configured to further promote tissueingrowth in the central region of the resultant implantable layer.

A lyophilization solution is provided around the dissolvable insert 2370in the mold cavity 2332 to form the lyophilized foam. Upon completion ofthe lyophilization process, the dissolvable insert 2370 is dissolved outof the resultant piece of lyophilized foam. A piece of lyophilized foamformed in the mold 2330 and with the dissolvable insert 2370 is depictedin FIG. 33. The lyophilized foam forms an implantable layer 2300comprising a porous body portion 2302 having a plurality of pores 2310defined therein. The implantable layer 2300 also includes a plurality oftissue ingrowth passages 2320 defined therein. The tissue ingrowthpassages 2320 define the voids remaining in the absence of thedissolvable insert 2370 (FIG. 31).

The tissue ingrowth passages 2320 comprise a plurality of verticalchannels, which correspond to the vertical spokes 2372, and webs ofhorizontal channels, which correspond to the horizontal spokes 2374. Aweb of horizontal channels is embedded in the body 2302 of theimplantable layer 2300. Another web of horizontal channels intersectsthe vertical channels along a face 2304 a of the implantable layer 2300.In use, the face 2304 a comprises a tissue-facing face and the tissueingrowth passages 2320 propagating therefrom are configured to promotethe ingrowth of tissue around, into and/or through the implantable layer2300. The tissue ingrowth channels 2320 are wider at the tissue-facingface 2304 a of the implantable layer 2300 than the opposing face of theimplantable layer 2300. Such structures are configured to furtherpromote and/or enhance tissue ingrowth.

In various instances, an implantable layer can be comprised of aplurality of non-flush layers. In such instances, voids and/or passagescan be defined between portions of adjacent layers in the implantablelayer. Such voids and/or passages provide inlets and/or passages fortissue ingrowth into the implantable layer. The voids and/or passagesalso provide ample space for deformation of the layers. The layers canbe comprised of a flexible and resilient material, which flexes under aload and rebounds upon removal of the load. For example, the layers canbe comprised of a compressible film, nonwoven material, and/or foam,such as lyophilized foam, for example. In various instances, theimplantable layer can comprise spring properties in a first directionand provide tissue ingrowth passages in a second direction that isperpendicular to the first direction. For example, the implantable layercan be compressible between a first face and a second, opposing, face,and the tissue ingrowth passages can extend between a third face and afourth, opposing, face. The third and fourth faces can be perpendicularto the first and second faces.

Referring primarily to FIG. 34, a portion of an implantable layer 2500is depicted. The implantable layer 2500 includes a plurality ofcorrugated layers 2502 a, 2502 b, 2502 c, 2502 d. Each corrugated layer2502 a, 2502 b, 2502 c, 2502 d comprises an undulating, fluted and/orpleated sheet 2506, and each fluted sheet 2506 comprises alternatingridges and grooves. The ridges and grooves in each sheet 2506 areparallel; however, the ridges and grooves in the sheet 2506 of at leastone corrugated layer 2502 a, 2502 b, 2502 c, 2502 d areangularly-oriented relative to the ridges and grooves in the sheet 2506of another corrugated layer 2502 a, 2502 b, 2502 c, 2502 d. For example,the ridges and grooves in the sheet 2506 of the first layer 2502 a arenon-parallel to the ridges and grooves in the sheet 2506 of the adjacentsecond layer 2502 b. In at least one instance, the ridges and grooves inthe sheet 2506 of the first layer 2502 a are perpendicular to the ridgesand grooves in the sheet 2506 of the adjacent second layer 2502 b.Additionally, the ridges and grooves in the sheet 2506 of the secondlayer 2502 b are perpendicular to the ridges and grooves in the sheet2506 of the adjacent third layer 2502 c, and the ridges and grooves inthe sheet 2506 of the third layer 2502 c are perpendicular to the ridgesand grooves in the sheet 2506 of the adjacent fourth layer 2502 d. Insuch instances, the corrugated layers 2502 a, 2502 b, 2502 c, and 2502 dare arranged in an alternating manner in which the ridges and grooves ofeach layer are perpendicular to the ridges and grooves of the adjacentlayers. A planar or substantially planar sheet 2508 is positionedbetween the fluted sheets 2506 in the implantable layer 2500, and asheet 2508 is also positioned on opposing faces 2504 of the implantablelayer 2500; however, embodiments are envisioned without one or more ofthe sheets 2508. In at least one embodiment, a stack of sinusoidal filmscan be used that create loft, or packing inefficiency, by not beingparallel and nested to one another. The peaks of the sine waves of onelayer will support the valleys of the sine waves above where theyintersect at discrete points. Further to the above, corrugates don'thave to be parallel or perpendicular to the primary axis of the deviceand/or knife slot. In at least one instance, corrugates are aligned+/−45 degrees to the primary axis of the staple reload.

Referring still to FIG. 34, owing to the corrugated structure of thelayers 2502 a, 2502 b, 2502 c, 2502 d, the implantable layer 2500comprises a minimal density and a plurality of voids and/or passages2520 for promoting tissue ingrowth. The implantable layer 2500 comprisesspring properties in a first direction (e.g. in the direction extendingbetween planar sheets 2508) and comprises tissue ingrowth passages insecond and third directions that are perpendicular to the firstdirection. The passages 2520 are defined by the ridges and grooves inthe fluted sheets 2506. As a result, the passages 2520 in each layer2502 a, 2502 b, 2502 c, 2502 d are parallel and the passages 2520 in alayer 2502 a, 2502 b, 2502 c, 2502 d are oriented perpendicular to thepassages 2520 in the adjacent layer or layers 2502 a, 2502 b, 2502 c,2502 d.

The implantable layer 2500 comprises four corrugated layers 2502 a, 2502b, 2502 c, 2502 d. In other instances, the implantable layer 2500 cancomprise less than four corrugated layers or more than four corrugatedlayers. For example, an implantable layer can comprise a singlecorrugated layer. The corrugated layers 2502 a, 2502 b, 2502 c, 2502 dof the implantable layer 2500 can be comprised of the same material. Inother instances, at least one of the corrugated layers 2502 a, 2502 b,2502 c, 2502 d can be comprised of a different material than at leastone other corrugated layer 2502 a, 2502 b, 2502 c, 2502 d. Additionallyor alternatively, an implantable layer can include at least onecorrugated layer 2502 a, 2502 b, 2502 c, 2502 d and at least onenon-corrugated layer. For example, at least one of the corrugated layers2502 a, 2502 b, 2502 c, 2502 d can be combined with a non-corrugatedfilm, foam layer, and/or fibrous layer.

In certain instances, at least one of the corrugated layers 2502 a, 2502b, 2502 c, 2502 d in the implantable layer 2500 can comprise a differentfluted and/or sinusoidal pattern than the other layers. For example, theridges and/or grooves can be steeper in at least one layer than in atleast one another layer. Additionally or alternatively, at least onelayer can comprise a different height than at least one other layer. Incertain instances, various fluted and/or sinusoidal layers can bestacked in parallel arrangement and/or in an angularly-oriented,non-perpendicular arrangement. In various instances, the corrugatedlayers can be multidirectional. For example, different layers can haveaxes of corrugation that are non-parallel to one another. At least onecorrugated layer can comprise a conical and/or pyramidal shape, forexample.

Referring again to FIG. 34, the implantable layer 2500 includes cutedges 2512. For example, the implantable layer 2500 can be cut from asheet of alternating pleated sheets 2506 and planar sheets 2508 and eachface of the implantable layer 2500 can be defined by a cut edge 2512,for example. The cut edges 2512 can be configured to provide a softand/or non-abrupt face, which may reduce and/or prevent trauma toadjacent tissue.

In certain instances, at least one of the corrugated layers 2502 a, 2502b, 2502 c, 2502 d can comprise a sinusoidal sheet. For example, at leastone of the sheets 2506 can comprise a repetitive oscillatory sinepattern. A sinusoidal sheet can be positioned between planar sheets2508. In certain instances, a sinusoidal sheet can be positioned inabutting engagement with another sinusoidal sheet. The adjacentsinusoidal sheets can form mirror image reflections, for example. Invarious instances, the frequency and/or the amplitude of the sine wavesin the sinusoidal sheet can be tuned to control the spring properties ofthe implantable layer and/or the size of the tissue ingrowth passagestherethrough.

Referring now to FIG. 35, a portion of a tissue thickness compensatingimplantable layer 2600 is depicted. The implantable layer 2600 includesa plurality of foam layers 2602 a, 2602 b, 2602 c, 2602 d and each layer2602 a, 2602 b, 2602 c, 2602 d includes at least one spacer 2606 forproviding a tissue ingrowth gap between adjacent layers 2602 a, 2602 b,2602 c, 2602 d in the implantable layer 2600. For example, the spacers2606 prevent the layers 2602 a, 2602 b, 2602 c, 2602 d from stackingflushly or flat relative to the adjacent layers 2602 a, 2602 b, 2602 c,2602 d. In other words, the spacers 2606 are configured to reduce thepacking efficiency of the layers 2602 a, 2602 b, 2602 c, 2602 d to lessthan 100%. The layers 2602 a, 2602 b, 2602 c, 2602 d can be combinedand/or secured together with at least one suture, adhesive, and/or aheat pressing technique, for example. One or more of the layers 2602 a,2602 b, 2602 c, 2602 d can be comprised of film.

The spacers 2606 comprise circular protrusions or nodes. In otherinstances, a spacer can comprise a ridge, bump, and/or an interlockingwaffle pattern of ridges, for example. Spacers can be positioned on oneor both sides of at least one of the foam, or film, layers 2602 a, 2602b, 2602 c, 2602 d to provide a tissue ingrowth gap therebetween. Spacerscan be created with lyophilization molds and/or felting operations, forexample. Referring now to FIG. 36, an implantable layer 2700 includes aplurality of nonwoven layers 2702 a, 2702 b, 2702 c, 2702 d. Spacers canbe added to the layers 2702 a, 2702 b, 2702 c, 2702 d using a feltingoperation, for example.

As described herein, the presence of different size voids (e.g. pores,or intrastitial voids, and tissue ingrowth passages, or interstitialvoids, and/or different sized pores) within an implantable layer maypromote the ingrowth of tissue around, into, and/or through theimplantable layer. In instances where a body portion of an implantablelayer is porous, additional tissue ingrowth inlets and/or passages canbe incorporated into the porous body portion to further facilitateand/or encourage tissue ingrowth. The additional tissue ingrowth inletsand/or passages can be integrally formed in the porous body portionduring the formation (e.g. lyophilization and/or molding) of the bodyportion. In other instances, tissue ingrowth inlets and/or passages canbe added during a secondary processing step, as further describedherein, for example.

In various instances, the addition of fibers to an implantable layer isconfigured to create additional tissue ingrowth inlets and/or passagesinto and/or within the body portion of the implantable layer. Morespecifically, when fibers are embedded within the body of an implantablelayer, the fibers can cause additional voids or pockets to form withinthe body. For example, when fibers are added to a lyophilizationsolution, the resultant piece of lyophilized foam can include aplurality of pores defined therein and a plurality of pockets definedtherein, wherein the pockets are larger than the pores. As furtherdescribed herein, the arrangement of pockets extending through theporous material can depend on the type of fibers and/or the arrangementof fibers embedded in the porous material.

Referring to FIG. 37, an implantable layer 3000 is depicted. Theimplantable layer 3000 comprises a tissue thickness compensator. Inother instances, the implantable layer 3000 comprises a piece ofbuttress material. The implantable layer 3000 includes a body 3002having an inner portion 3006 and an outer portion 3008. The outerportion 3008 surrounds the inner portion 3006 such that the innerportion 3006 is defined within the boundary of the outer portion 3008.The outer portion 3008 includes a plurality of faces or sides 3004,which define the perimeter of the body 3002. In various instances, thebody 3002 of the implantable layer 3000 comprises a rectangular prismhaving six faces including a first face 3004 a. In other instances, thebody 3002 can comprise a triangular prism or another three-dimensionalshape, for example. In the depicted embodiment, the first face 3004 acorresponds to a tissue-contacting surface of the implantable layer3000. In other instances, the first face 3004 a can correspond to adeck-contacting surface and/or a sidewall of the body 3002, for example.

The body 3002 of the implantable layer 3000 is a porous body. Forexample, the body 3002 comprises a piece of foam having a plurality ofpores 3010 defined therein. In various instances, the body 3002 is apiece of lyophilized foam. The lyophilized foam can comprisepolyglycolic acid (PGA) and/or polycaprolactone (PCL), for example. Thebody 3002 comprises an open cellular structure. For example, a pore 3010a is adjacent to the first face 3004 a of the body 3002 and the boundaryof the pore 3010 a defines an outer surface of the body 3002. Open cellpores, such as the pore 3010 a, for example, can provide a tissueingrowth inlet and/or a foothold for tissue ingrowth. In otherembodiments, the body 3002 can comprise a closed-cell structure. In suchinstances, the pores 3010 can be positioned entirely within the body3002. Closed-cell pores are not open to an outer surface or face 3004 ofthe body 3002.

The body 3002 includes a plurality of fibers 3009. The fibers 3009 areembedded within the body 3002. Moreover, the fibers 3009 are randomlyoriented and intertwined within the body 3002. Some fibers 3009terminate within the inner portion 3006 of the body 3002, other fibers3009 extend to the outer portion 3008 of the body 3002, and some fiber3009 protrude beyond one of the faces 3004 of the body 3002. In otherwords, various fibers 3009 are embedded entirely within the body 3002and other fibers 3009 are only partially embedded within the body 3002.

The various fibers 3009 depicted in FIG. 37 define differentcross-sectional shapes and/or dimensions. For example, certain fibers3009 are thicker than other fibers 3009. The fibers 3009 are loosefibers that randomly meet, cross, and/or curve. For example, the fibers3009 can be non-woven fibers, such as melt-blown non-woven fibers. Thefibers 3009 can be comprised of VICRYL® manufactured by Ethicon Inc.,for example. In certain instances, the fibers 3009 can be interwoven.For example, the fibers 3009 can comprise a fibrous mesh within the body3002.

The body 3002 also includes tissue ingrowth pockets 3020. The pockets3020 are positioned around the fibers 3009. For example, the porous body3002 and the fibers 3009 can comprise a phobic relationship, in whichthe fibers 3009 repel the body 3002 or vice versa. As a result, thepockets 3020 can separate the fibers 3009 from direct contact with theporous body 3002. The porous body 3002 can comprise arrays of porousregions that extend from the area around the fibers 3009 and crash intoother porous regions and/or terminate at a pocket 3020 surrounding anadjacent fiber 3009.

The pockets 3020 are configured to follow the path of the fibers 3009extending through the porous body 3002. Various passages formed by thepockets 3020 are oriented at different angles within the body 3002 andpropagate in different directions within the body 3002. For example, apocket 3020 can follow the curvature of the fiber 3009 disposed therein.The pockets 3020 are also configured to intersect where the fibers 3009meet and/or closely cross paths within the body 3002. The size of thepockets 3020 can expand or grow in an additive manner where the pockets3020 intersect. As a result, different size pockets or voids occurwithin the body 3002. Moreover, because the pockets 3020 follow the pathof the fibers 3009, the pockets 3020 define passages and/or canalswithin the body 3002. In instances where one of the fibers 3009 extendsto a face 3004 of the body 3002, the corresponding pocket 3020 alsoextends to the same face 3004 of the body 3002. Such a pocket 3020comprises an open-cell pocket. In instances where the fiber 3009 isentirely embedded within the body 3002, the corresponding pocket 3020can be positioned entirely within the body 3002. Such a pocket 3020comprises a closed-cell pocket.

In various instances, a passage can extend between faces 3004 of thebody 3002. For example, a single fiber 3009 and corresponding pocket3020 can extend through the body 3002. In other instances, two or morepockets 3020 within the body 3002 can intersect or combine to extend apassage entirely through the body 3002. Because the pockets 3020 arelarger than the pores 3010 defined in the porous body 3002, at least onepocket 3020 can entirely consume one or more of the pores 3010.

In various instances, the passages formed by the pockets 3020 within thebody 3002 are conducive to tissue ingrowth. Specifically, tissue isencouraged to grow and/or propagate along the passages. In instanceswhere the passages begin at a face 3004 of the implantable layer 3000,such as the tissue-facing face 3004 a, the passages are configured toencourage the ingrowth of tissue from the outer portion 3008 of the body3002 toward and/or into the inner portion 3006 of the body 3002. In atleast one instance, the varied orientation of the passages is configuredto promote the integration of the implantable layer 3000 into thesurrounding tissue.

In various instances, the fibers 3009 can comprise a first absorption ordegradation rate and the body 3002 can comprise a second absorption ordegradation rate that is different than the first rate. In suchinstances, portions of the implantable layer 3000 can degrade atdifferent rates. For example, the fibers 3009 can degrade, orsubstantially degrade, before the body 3002 degrades, or substantiallydegrades. In such instances, after degradation of the fibers 3009, thepockets 3020 can define an additional volume within the body 3002 priorto the degradation of the body 3002, which may enhance and/or acceleratetissue ingrowth. In certain instances, the degradation rates can beselected to tune various properties of the implantable layer 3000. Forexample, where the fibers 3009 provide significant spring-like qualitiesto the implantable layer 3000 and the body 3002 provides a scaffoldingand/or buttressing property to the implantable layer 3000, the durationof the spring properties and the scaffolding properties can be tunedindependently. In at least one instance, the springiness of theimplantable layer 3000 can be sacrificed before the buttressing providedby the body 3002 is sacrificed. In other instances, the buttressingprovided by the body 3002 can be sacrificed before the springinessprovided by the fibers 3009 is sacrificed. The reader will appreciatethat additional and/or different properties of the implantable layer3000 may be tuned based on the absorption rate of the porous body 3002and/or the fibers 3009 embedded therein.

In various instances, a lyophilized foam body, such as the body 3002,can include substantially smooth and/or flat surface portions and/orscalloped pore surfaces. Such surfaces may discourage cell adhesion.However, the fibers 3009 and the inlets to the pockets 3020 at theface(s) 3004 of the implantable body 3002 provide additional textureand/or sufficient inlets to the body 3002, which are configured topromote cell adhesion and/or cell motility. Additionally, fibrous tissuemay more readily attach to a fibrous structure, such as the fibers 3009positioned at the face(s) 3004 of the body 3002, than to thesubstantially smooth, flat and/or scalloped pore surfaces of the body3002. As a result, the ingrowth of tissue along the passages formed bythe intertwined and/or interconnected pockets 3020 in the body 3002 canbe promoted by the texture and/or shapes formed along the face(s) of aporous body 3002 having fibers 3009 embedded therein and/or extendingtherefrom.

Referring primarily now to FIG. 38, a portion of a staple cartridge 3150is shown. The staple cartridge 3150 includes a cartridge body 3152having a deck 3156. A plurality of staple cavities are defined in thecartridge body 3152, and each staple cavity comprises an opening in thedeck 3156. For example, a staple cavity 3154 is defined in the cartridgebody 3152. The staple cartridge 3150 further includes a plurality ofstaples. For example, a staple 3160 is positioned in the staple cavity3154. The staple cartridge 3150 includes an implantable layer 3100,which is positioned adjacent to the deck 3156 of the cartridge body3152. The implantable layer 3100 extends over the openings in the deck3156. The implantable layer 3100 can be releasably positioned relativeto the deck 3156.

Referring to FIGS. 38 and 39, the implantable layer 3100 comprises atissue thickness compensator. The implantable layer 3100 comprises aporous body 3102 having a plurality of fibers 3109 embedded therein.Additionally, the implantable layer 3100 comprises a plurality ofpockets or passages 3120 that extend around the fibers 3109. Theimplantable layer 3100 also includes a first face 3104 a and a secondface 3104 b. The first face 3104 a comprises a tissue-contactingsurface. For example, during a stapling operation, tissue T ispositioned against and compressed against the first face 3104 a of theimplantable layer 3100. The second face 3104 b is opposite to the firstface 3104 a. More particularly, in the orientation depicted in FIG. 38,the first face 3104 a comprises a top surface of the implantable layer3100, and the second face 3104 b comprises a bottom surface of theimplantable layer 3100. At least one passage 3120 in the implantablelayer 3100 extends between the opposing first face 3104 a and secondface 3104 b. Such passages 3120 provide pathways for tissue ingrowthbetween opposing sides of the implantable layer 3100 (e.g. between thetop surface and the bottom surface).

During a stapling operation, tissue T is captured within the staple 3160along with a portion of the implantable layer 3100. The tissue T and theimplantable layer 3100 are compressed within the fired and deformedstaple 3160 (FIG. 39). As depicted in FIG. 39, the height of thecompressed implantable layer 3100 varies within the formed staple 3160in response to various properties of the adjacent tissue T. For example,the implantable layer 3100 is configured to assume a greater heightwhere the captured tissue T is thinner and is configured to assume alesser height where the captured tissue T is thicker. The reader willfurther appreciate that the height of the compressed implantable layer3100 can also vary from staple to staple in a staple line and/or in theunstapled regions between adjacent staples in the staple line inresponse to various properties of the tissue T.

Referring now to FIG. 40, a portion of an implantable layer 3200 isdepicted. The implantable layer 3200 comprises a tissue thicknesscompensator. In other embodiments, the implantable layer 3200 comprisesa piece of buttress material. The implantable layer 3200 includes a body3202, which is comprised of a porous material. For example, the body3202 comprises a piece of foam having a plurality of pores definedtherein. In various instances, the body 3202 is a piece of lyophilizedfoam. The lyophilized foam can comprise polyglycolic acid (PGA) and/orpolycaprolactone (PCL), for example. In various instances, the porousbody 3202 comprises an open cellular structure.

The implantable layer 3200 also includes a plurality of fibers 3209,which are embedded within the porous body 3202. The fibers 3209 arearranged in an interwoven pattern. For example, the fibers 3209 create athree-dimensional mesh within the body 3202. The porous body 3202 andthe fibers 3209 comprise a philic relationship, in which the fibers 3209attract the body 3202 or vice versa. As a result, the body 3202 clingsto the fibers 3209 and the fibers 3209 are encased by the body 3202. Inother words, the implantable layer 3200 includes a plurality offoam-encased fibers 3209. The implantable layer 3200 also includes aplurality of pockets 3220. Because the body 3202 is immediately adjacentto the fibers 3209, the pockets 3220 are positioned intermediateportions of the body 3202. Various pockets 3220 intersect within theimplantable layer 3200 to form a plurality of tissue ingrowth passages.A passage can extend between faces of the body 3202.

The passages formed by the pockets 3220 within the body 3022 areconducive to tissue ingrowth. Specifically, tissue is encouraged to growand/or propagate along the passages. In instances where the passagesbegin at a face of the implantable layer, such as a tissue-contactingface, the passages are configured to encourage the ingrowth of tissuefrom the outer portion of the implantable layer 3200 toward and/or intothe inner portion of the implantable layer 3202. In at least oneinstance, the varied orientation of the passages (e.g. horizontal,vertical, and diagonal within the implantable layer 3200) promotes theintegration of the implantable layer 3200 into the surrounding tissue.

Referring now to FIG. 41, a mold 3330 for forming a piece of lyophilizedfoam is depicted. The mold 3330 comprises sidewalls 3331 defining acavity 3332 for receiving a lyophilization solution 3340. The cavity3332 can comprise a geometry that corresponds to the desired geometry ofan implantable layer and/or a body portion thereof. In other instances,a piece and/or sheet of implantable material can be formed in the moldcavity 3332, and the molded piece and/or sheet can be cut and/orotherwise trimmed to the desired size and/or shape.

A lyophilization solution 3340 is provided to the mold cavity 3332. Thelyophilization solution 3340 includes a plurality of fibers 3309. Inother words, the fibers 3309 are injected into the mold cavity 3332along with the lyophilization solution 3340. After the lyophilizationsolution 3340 and fibers 3309 have been added to the mold cavity 3332,the solution 3340 is lyophilized to form a piece of lyophilized foamhaving pores and pockets defined therein. In certain instances, thelyophilization solution 3340 can cling to the fibers 3309 distributedtherein forming tissue ingrowth pockets between adjacent regions of thesolution 3340 (i.e. between portions of the resultant porous body) and,in other instances, the fibers 3309 can repel the lyophilizationsolution 3340 forming tissue ingrowth pockets between the fibers 3309and the solution 3340 (i.e. surrounding the embedded fibers 3309).

Referring now to FIGS. 42-44, a lyophilization solution can beinsert-molded around a plurality of fibers to form an implantable layeror a portion thereof. For example, in the embodiment depicted in FIGS.42-44, a mold 3430 comprising sidewalls 3431 and a cavity 3432 is shown.A plurality of loose fibers 3409 are positioned in the mold cavity 3432.The fibers 3409 are randomly oriented within the mold cavity 3432, and alyophilization solution 3440 (FIGS. 42 and 43) is injected into the moldcavity 3432 around the fibers 3409. As shown in FIG. 43, thelyophilization solution 3440 fills the voids between the fibers 3409.Thereafter, the solution 3440 is lyophilized to form a piece oflyophilized foam 3400 (FIG. 44) having pores and tissue ingrowth pocketsdefined therein. In addition to or in lieu of the above, fibers can bemixed into the solution 3440 prior to the solution being poured into themold cavity 3432. In any event, the lyophilized foam 3400 includes aporous body 3402 formed from the lyophilization solution 3440 (FIGS. 42and 43). Referring primarily now to FIG. 44, the fibers 3409 providecrystal initiation points for the lyophilization solution 3440. As aresult, porous arrays propagate from the fibers 3409 in differentdirections to form random arrays that crash into each other and/orterminate at tissue ingrowth pockets surrounding the embedded fibers3409.

In the embodiment depicted in FIGS. 45 and 46, a mold 3530 comprisingsidewalls 3531 and a cavity 3532 is shown. A plurality of woven fibers3509 are positioned in the mold cavity 3532. The fibers 3509 are woveninto a three-dimensional web or mesh positioned within the mold cavity3532, and a lyophilization solution 3540 (FIG. 45) is injected into themold cavity 3532 around the fibers 3509. The lyophilization solution3540 is configured to fill the voids between the woven fibers 3509.Thereafter, the solution 3540 is lyophilized to form a piece oflyophilized foam 3500 (FIG. 46) having pores and tissue ingrowth pocketsdefined therein. The lyophilized foam 3500 includes a porous body 3502formed from the lyophilization solution 3540 (FIG. 45). Referringprimarily now to FIG. 46, the fibers 3509 provide crystal initiationpoints for the lyophilization solution 3540. As a result, porous arrayspropagate from the fibers 3509 in different directions to form a systemof porous arrays that crash into each other and/or terminate at tissueingrowth pockets surrounding the embedded fibers 3509.

In various instances, a lyophilization solution, such as thelyophilization solutions 3340, 3440, and 3540, for example, can includeat least one nucleation initiator. For example, a binary solvent ofdioxane and water can be added to the lyophilization solution. The waterpercentage of the binary solvent can be between approximately 1% and15%, for example. In other instances, the water percentage can be lessthan 1% or greater than 15%. The lyophilization solution is created bydissolving a polymer, such as PCL/PGA, for example, in the solvent, suchas dioxane, for example. In at least one such instance, this is donewith between approximately 2% to approximately 15% polymer, for example,and between approximately 98% to approximately 85% solvent, for example.In one exemplary dioxane/water binary solvent system, approximately 90%dioxane and approximately 10% water is preferred with approximately 85%dioxane and approximately 15% water as the limit. The nucleationinitiator is configured to promote the formation of different sizedpores in the lyophilization solution and in the resultant piece oflyophilized foam. For example, the addition of a nucleation initiator isconfigured to create a mix of large and small pores in thelyophilization solution and in the resultant piece of lyophilized foam.When the lyophilized foam is implanted into a patient, as furtherdescribed herein, the variation in pore size can encourage tissueingrowth. In at least one instance, tissue ingrowth can begin in alarger pore, gain traction within the implantable layer, and extend intoat least one smaller pore.

In certain instances, additional materials can be added to alyophilization solution, such as the lyophilization solutions 3340,3440, and 3540, for example. For example, stearates can be incorporatedinto a lyophilization solution to provide lubrication. Additionally oralternatively, antibiotics can be incorporated into a lyophilizationsolution to reduce infection potentiation. For example, triclosan and/orsilver beads can be added to a lyophilization solution to further reducethe risk of infection. Colloidal silver and/or silver-impregnated fiberscould also be used in a lyophilization solution. Additionally oralternatively, radiopaque materials can be incorporated into alyophilization solution to facilitate CT and/or x-ray visualization. Forexample, iopamidol can be added to a lyophilization solution. In variousinstances, additional and/or different materials can be incorporatedinto a lyophilization solution to obtain additional and/or differentbenefits.

The surgical instrument systems described herein have been described inconnection with the deployment and deformation of staples; however, theembodiments described herein are not so limited. Various embodiments areenvisioned which deploy fasteners other than staples, such as clamps ortacks, for example. Moreover, various embodiments are envisioned whichutilize any suitable means for sealing tissue. For instance, an endeffector in accordance with various embodiments can comprise electrodesconfigured to heat and seal the tissue. Also, for instance, an endeffector in accordance with certain embodiments can apply vibrationalenergy to seal the tissue.

EXAMPLES Example 1

A staple cartridge comprising a cartridge body comprising a plurality ofstaple cavities, a plurality of staples removably positioned in thestaple cavities, and a porous implantable layer. The porous implantablelayer comprises an inner portion, an outer portion positioned at leastpartially around the inner portion, and a plurality of passages formedthrough the outer portion toward the inner portion.

Example 2

The staple cartridge of Example 1, wherein the plurality of passagescomprises a first passage and a second passage angularly-orientedrelative to the first passage.

Example 3

The staple cartridge of Example 2, wherein the second passage traversesthe first passage.

Example 4

The staple cartridge of Examples 1, 2, or 3, wherein at least one of thepassages extends through the porous implantable layer.

Example 5

The staple cartridge of Examples 1, 2, 3, or 4, wherein the outerportion comprises a tissue-contacting surface, and wherein at least oneof the passages extends through the tissue-contacting surface.

Example 6

The staple cartridge of Examples 1, 2, 3, 4, or 5, wherein the porousimplantable layer comprises a lyophilized foam material.

Example 7

The staple cartridge of Example 6, wherein the lyophilized foam materialcomprises an open cellular structure.

Example 8

The staple cartridge of Examples 6 or 7, wherein at least one of thepassages comprises a punched hole.

Example 9

The staple cartridge of Examples 6, 7, or 8, wherein the outer portioncomprises a surface treatment.

Example 10

A method of forming an implantable layer for use with a surgicalstapler, the method comprising, one, obtaining a piece of lyophilizedfoam, wherein the piece of lyophilized foam comprises an inner portionand an outer surface, and, two, forming at least one passage through theouter surface toward the inner portion.

Example 11

The method of Example 10, wherein forming at least one passage throughthe outer surface toward the inner portion comprises a mechanicalpunching treatment.

Example 12

The method of Examples 10 or 11, wherein forming at least one passagethrough the outer surface toward the inner portion comprises a lasertreatment.

Example 13

The method of Examples 10, 11, or 12, wherein forming at least onepassage through the outer surface toward the inner portion comprises aradiation treatment.

Example 14

The method of Examples 10, 11, 12, or 13, wherein forming at least onepassage through the outer surface toward the inner portion comprisesapplying a surface treatment to the outer surface, wherein the surfacetreatment is selected from a group consisting of etching, blasting,grinding, milling, and combinations thereof.

Example 15

The method of Examples 10, 11, 12, 13, or 14, wherein forming at leastone passage through the outer surface toward the inner portion comprisesforming a first passage and forming a second passage that traverses thefirst passage in the inner portion.

Example 16

The method of Example 15, wherein the outer surface comprises a firstface of the piece of lyophilized foam and a second face of the piece oflyophilized foam, wherein the first face is angularly-oriented relativeto the second face, wherein the first passage extends from the firstface of the outer surface, and wherein the second passage extends fromthe second face of the outer surface.

Example 17

A staple cartridge comprising a cartridge body comprising a plurality ofstaple cavities, a plurality of staples removably positioned in thestaple cavities, and an implantable layer. The implantable layercomprises, one, an inner portion comprising a piece of foam and, two, anouter portion comprising a plurality of fibers, wherein the outerportion is positioned at least partially around the inner portion.

Example 18

The staple cartridge of Example 17, wherein the fibers form a wovenpocket, and wherein the woven pocket is positioned around the innerportion.

Example 19

The staple cartridge of Examples 17 or 18, wherein the fibers form awoven layer, and wherein the woven layer is secured to the piece offoam.

Example 20

The staple cartridge of Example 19, wherein the implantable layercomprises a tissue-contacting surface, and wherein the woven layercomprises at least a portion of the tissue-contacting surface.

Example 21

A staple cartridge comprising a cartridge body comprising a plurality ofstaple cavities, a plurality of staples removably positioned in thestaple cavities, and an implantable layer comprising a plurality of foamfragments, wherein each of the foam fragments is fused to at least oneof the other of the foam fragments to form a unitary body.

Example 22

The staple cartridge of Example 21, wherein the implantable layerfurther comprises a plurality of intrastitial voids intermediate thefoam fragments and a plurality of interstitial voids within the foamfragments.

Example 23

The staple cartridge of Examples 21 or 22, wherein the foam fragmentsare randomly oriented throughout the implantable layer.

Example 24

The staple cartridge of Examples 21, 22, or 23, wherein the plurality offoam fragments comprises a first foam fragment comprising a firstporosity and a second foam fragment comprising a second porosity,wherein the second porosity is different than the first porosity.

Example 25

The staple cartridge of Examples 21, 22, 23, or 24, wherein theplurality of foam fragments comprises a first foam fragment comprising afirst geometry and a second foam fragment comprising a second geometry,wherein the second geometry is different than the first geometry.

Example 26

The staple cartridge of Examples 21, 22, 23, 24, or 25, wherein theplurality of foam fragments comprises a first foam fragment comprising afirst material and a second foam fragment comprising a second material,wherein the second material is different than the first material.

Example 27

The staple cartridge of Examples 21, 22, 23, 24, 25, or 26, wherein theplurality of foam fragments comprises a first foam fragment comprising afirst absorption rate and a second foam fragment comprising a secondabsorption rate, wherein the second absorption rate is different thanthe first absorption rate.

Example 28

The staple cartridge of Examples 21, 22, 23, 24, 25, 26, or 27, whereinthe implantable layer further comprises at least one medicament.

Example 29

The staple cartridge of Examples 21, 22, 23, 24, 25, 26, 27, or 28,wherein the implantable layer further comprises a plurality of fibers.

Example 30

The staple cartridge of Examples 21, 22, 23, 24, 25, 26, 27, 28, or 29,wherein the plurality of foam fragments comprises a first foam fragmentcomprising a first medicament and a second foam fragment comprising asecond medicament, wherein the second medicament is different than thefirst medicament.

Example 31

A method of forming an implantable layer for use with a surgicalstapler, the method comprising obtaining a plurality of foam fragments,heating the foam fragments, and compressing the foam fragments.

Example 32

The method of Example 31, wherein obtaining the plurality of foamfragments comprises grinding at least one piece of foam to form theplurality of foam fragments.

Example 33

The method of Examples 31 or 32, further comprising sorting theplurality of foam fragments.

Example 34

The method of Examples 31, 32, or 33, wherein heating the foam fragmentscomprises heating the foam fragments to a temperature above a glasstransition temperature of the foam fragments and below a meltingtemperature of the foam fragments.

Example 35

The method of Examples 31, 32, 33, or 34, wherein heating the foamfragments and compressing the foam fragments occurs simultaneously.

Example 36

The method of Examples 31, 32, 33, 34, or 35, wherein the plurality offoam fragments comprises a first foam fragment comprising a firstmedicament and a second foam fragment comprising a second medicament,wherein the second medicament is different than the first medicament.

Example 37

The method of Examples 31, 32, 33, 34, 35, or 36, further comprisingobtaining at least one adjunct and combining the at least one adjunctwith the foam fragments before heating the foam fragments and beforecompressing the foam fragments.

Example 38

The method of Example 37, wherein the at least one adjunct is selectedfrom a group consisting of an antibacterial adjunct, a fibrous adjunct,a collagen adjunct, and combinations thereof.

Example 39

A method of forming an implantable layer for use with a surgicalstapler, the method comprising obtaining a mold comprising a cavity,generating bubbles within a solution, dispensing the solution into thecavity of the mold, and lyophilizing the solution in the cavity.

Example 40

The method of Example 39, further comprising applying vibrations to themold after dispensing the solution into the cavity.

Example 41

The method of Examples 39 or 40, wherein generating bubbles within thesolution comprises whipping the solution.

Example 42

A method of forming an implantable layer for use with a surgicalstapler, the method comprising obtaining an insert mold comprising afirst cavity, forming a dissolvable insert in the first cavity of theinsert mold, removing the dissolvable insert from the first cavity,obtaining a layer mold comprising a second cavity, placing thedissolvable insert in the second cavity of the layer mold, dispensing asolution into the second cavity around the dissolvable insert, andlyophilizing the solution in the second cavity.

Example 43

A staple cartridge comprising a cartridge body comprising a plurality ofstaple cavities, a plurality of staples removably positioned in thestaple cavities, and an implantable layer. The implantable layercomprises a piece of lyophilized foam and a plurality of fibers at leastpartially embedded in the piece of lyophilized foam.

Example 44

The staple cartridge of Example 43, wherein the implantable layercomprises a plurality of pores defined in the piece of lyophilized foamand a plurality of pockets, wherein a pocket at least partiallysurrounds a fiber.

Example 45

The staple cartridge of Example 44, wherein the plurality of pocketscomprises a first pocket and a second pocket transecting the firstpocket.

Example 46

The staple cartridge of Examples 43, 44, or 45, wherein the fibers arerandomly oriented throughout the piece of lyophilized foam.

Example 47

The staple cartridge of Examples 43, 44, 45, or 46, wherein the fiberscomprise an ordered matrix of fibers in the piece of lyophilized foam.

Example 48

The staple cartridge of Examples 43, 44, 45, 46, or 47, wherein thefibers comprise a first fiber comprising a first geometry and a secondfiber comprising a second geometry, wherein the second geometry isdifferent than the first geometry.

Example 49

The staple cartridge of Examples 43, 44, 45, 46, 47, or 48, wherein thefibers comprise a first fiber comprising a first material and a secondfiber comprising a second material, wherein the second material isdifferent than the first material.

Example 50

The staple cartridge of Examples 43, 44, 45, 46, 47, 48, or 49, whereinthe foam of the piece of lyophilized foam encases and adheres to thefibers forming a plurality of foam-encased fibers.

Example 51

The staple cartridge of Example 50, wherein the implantable layercomprises a plurality of pores defined in the piece of lyophilized foamand a plurality of pockets, wherein each of the pockets is intermediateat least two of the foam-encased fibers.

Example 52

The staple cartridge of Examples 43, 44, 45, 46, 47, 48, 49, 50, or 51,wherein the piece of lyophilized foam comprises a first absorption rate,wherein at least one of the fibers comprises a second absorption rate,and wherein the second absorption rate is different than the firstabsorption rate.

Example 53

The staple cartridge of Examples 43, 44, 45, 46, 47, 48, 49, 50, 51, or52, wherein the implantable layer comprises a tissue-contacting surface,and wherein at least one of the fibers extends to the tissue-contactingsurface.

Example 54

A method of forming an implantable layer for use with a surgicalstapler, the method comprising obtaining a mold comprising a cavity,placing a plurality of fibers in the cavity of the mold, dispensing asolution into the cavity around the fibers, and lyophilizing thesolution in the cavity.

Example 55

The method of Example 54, wherein placing the plurality of fibers in thecavity comprises placing a woven mesh of fibers into the cavity.

Example 56

The method of Examples 54 or 55, wherein placing the plurality of fibersin the cavity comprises placing a plurality of loose fibers into thecavity.

Example 57

The method of Examples 54, 55, or 56, wherein the solution comprisesdioxane and water.

Example 58

The method of Examples 54, 55, 56, or 57, wherein the solution comprisesat least one medicament.

Example 59

A staple cartridge comprising a cartridge body comprising a plurality ofstaple cavities, a plurality of staples removably positioned in thestaple cavities, and an implantable layer. The implantable layercomprises, one, a porous foam comprising a plurality of pores and, two,a plurality of pockets defined between portions of the porous foam.

Example 60

The staple cartridge of Example 59, wherein the implantable layerfurther comprises a plurality of fibers at least partially embedded inthe porous foam.

Example 61

The staple cartridge of Example 60, wherein the pockets at leastpartially surround the fibers.

Example 62

The staple cartridge of Examples 60 or 61, wherein the foam encases thefibers.

Although the various embodiments of the devices have been describedherein in connection with certain disclosed embodiments, manymodifications and variations to those embodiments may be implemented.Also, where materials are disclosed for certain components, othermaterials may be used. Furthermore, according to various embodiments, asingle component may be replaced by multiple components, and multiplecomponents may be replaced by a single component, to perform a givenfunction or functions. The foregoing description and following claimsare intended to cover all such modification and variations.

The devices disclosed herein can be designed to be disposed of after asingle use, or they can be designed to be used multiple times. In eithercase, however, the device can be reconditioned for reuse after at leastone use. Reconditioning can include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, the devicecan be disassembled, and any number of the particular pieces or parts ofthe device can be selectively replaced or removed in any combination.Upon cleaning and/or replacement of particular parts, the device can bereassembled for subsequent use either at a reconditioning facility, orby a surgical team immediately prior to a surgical procedure. Thoseskilled in the art will appreciate that reconditioning of a device canutilize a variety of techniques for disassembly, cleaning/replacement,and reassembly. Use of such techniques, and the resulting reconditioneddevice, are all within the scope of the present application.

By way of example only, aspects described herein may be processed beforesurgery. First, a new or used instrument may be obtained and whennecessary cleaned. The instrument may then be sterilized. In onesterilization technique, the instrument is placed in a closed and sealedcontainer, such as a plastic or TYVEK bag. The container and instrumentmay then be placed in a field of radiation that can penetrate thecontainer, such as gamma radiation, x-rays, or high-energy electrons.The radiation may kill bacteria on the instrument and in the container.The sterilized instrument may then be stored in the sterile container.The sealed container may keep the instrument sterile until it is openedin a medical facility. A device also may be sterilized using any othertechnique known in the art, including but not limited to beta or gammaradiation, ethylene oxide, plasma peroxide, or steam.

While this invention has been described as having exemplary designs, thepresent invention may be further modified within the spirit and scope ofthe disclosure. This application is therefore intended to cover anyvariations, uses, or adaptations of the invention using its generalprinciples.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

What is claimed is:
 1. A staple cartridge, comprising: a cartridge bodycomprising a plurality of staple cavities; a plurality of staplesremovably positioned in said staple cavities; and an implantable layer,comprising: a piece of lyophilized foam; and a plurality of fibers atleast partially embedded in said piece of lyophilized foam.
 2. Thestaple cartridge of claim 1, wherein said implantable layer comprises: aplurality of pores defined in said piece of lyophilized foam; and aplurality of pockets, wherein a said pocket at least partially surroundsa said fiber.
 3. The staple cartridge of claim 2, wherein said pluralityof pockets comprises: a first pocket; and a second pocket transectingsaid first pocket.
 4. The staple cartridge of claim 1, wherein saidfibers are randomly oriented throughout said piece of lyophilized foam.5. The staple cartridge of claim 1, wherein said fibers comprise anordered matrix of fibers in said piece of lyophilized foam.
 6. Thestaple cartridge of claim 1, wherein said fibers comprise: a first fibercomprising a first geometry; and a second fiber comprising a secondgeometry, wherein said second geometry is different than said firstgeometry.
 7. The staple cartridge of claim 1, wherein said fiberscomprise: a first fiber comprising a first material; and a second fibercomprising a second material, wherein said second material is differentthan said first material.
 8. The staple cartridge of claim 1, whereinthe foam of said piece of lyophilized foam encases and adheres to saidfibers forming a plurality of foam-encased fibers.
 9. The staplecartridge of claim 8, wherein said implantable layer comprises: aplurality of pores defined in said piece of lyophilized foam; and aplurality of pockets, wherein each said pocket is intermediate at leasttwo foam-encased fibers.
 10. The staple cartridge of claim 1, whereinsaid piece of lyophilized foam comprises a first absorption rate,wherein at least one said fiber comprise a second absorption rate, andwherein said second absorption rate is different than said firstabsorption rate.
 11. The staple cartridge of claim 1, wherein saidimplantable layer comprises a tissue-contacting surface, and wherein atleast one said fiber extends to said tissue-contacting surface.
 12. Amethod of forming an implantable layer for use with a surgical stapler,the method comprising: obtaining a mold comprising a cavity; placing aplurality of fibers in the cavity of the mold; dispensing a solutioninto the cavity around the fibers; and lyophilizing the solution in thecavity.
 13. The method of claim 12, wherein placing the plurality offibers in the cavity comprises placing a woven mesh of fibers into thecavity.
 14. The method of claim 12, wherein placing the plurality offibers in the cavity comprises placing a plurality of loose fibers intothe cavity.
 15. The method of claim 12, wherein the solution comprisesdioxane and water.
 16. The method of claim 12, wherein the solutioncomprises at least one medicament.
 17. A staple cartridge, comprising: acartridge body comprising a plurality of staple cavities; a plurality ofstaples removably positioned in said staple cavities; and an implantablelayer, comprising: a porous foam comprising a plurality of pores; and aplurality of pockets defined between portions of said porous foam. 18.The staple cartridge of claim 17, wherein said implantable layer furthercomprises a plurality of fibers at least partially embedded in saidporous foam.
 19. The staple cartridge of claim 18, wherein said pocketsat least partially surround said fibers.
 20. The staple cartridge ofclaim 18, wherein said foam encases said fibers.